diff --git a/README.md b/README.md
index 98ec1e634..b288d3b72 100644
--- a/README.md
+++ b/README.md
@@ -95,6 +95,24 @@ When the CLI is launched, it logs if a newer version of the CLI is available. Yo
 
 When the CLI is launched, it logs a warning if there are any ongoing [GitHub incidents](https://www.githubstatus.com/) that might affect your use of the CLI. You can skip this check by setting the `GEI_SKIP_STATUS_CHECK` environment variable to `true`. 
 
+### Configuring multipart upload chunk size
+
+Set the `GITHUB_OWNED_STORAGE_MULTIPART_MEBIBYTES` environment variable to change the archive upload part size. Provide the value in mebibytes (MiB); For example:
+
+```powershell
+# Windows PowerShell
+$env:GITHUB_OWNED_STORAGE_MULTIPART_MEBIBYTES = "10"
+```
+
+```bash
+# macOS/Linux
+export GITHUB_OWNED_STORAGE_MULTIPART_MEBIBYTES=10
+```
+
+This sets the chunk size to 10 MiB (10,485,760 bytes). The minimum supported value is 5 MiB, and the default remains 100 MiB.
+
+This might be needed to improve upload reliability in environments with proxies or very slow connections.
+
 ## Contributions
 
 See [Contributing](CONTRIBUTING.md) for more info on how to get involved.
diff --git a/RELEASENOTES.md b/RELEASENOTES.md
index 8b1378917..6da37fb47 100644
--- a/RELEASENOTES.md
+++ b/RELEASENOTES.md
@@ -1 +1 @@
-
+- Added support for configurable multipart upload chunk size for GitHub-owned storage uploads via `GITHUB_OWNED_STORAGE_MULTIPART_MEBIBYTES` environment variable (minimum 5 MiB, default 100 MiB) to improve upload reliability in environments with proxies or slow connections
\ No newline at end of file
diff --git a/src/Octoshift/Factories/GithubApiFactory.cs b/src/Octoshift/Factories/GithubApiFactory.cs
index 8e6c24582..962e5e132 100644
--- a/src/Octoshift/Factories/GithubApiFactory.cs
+++ b/src/Octoshift/Factories/GithubApiFactory.cs
@@ -32,7 +32,7 @@ GithubApi ISourceGithubApiFactory.Create(string apiUrl, string uploadsUrl, strin
         uploadsUrl ??= DEFAULT_UPLOADS_URL;
         sourcePersonalAccessToken ??= _environmentVariableProvider.SourceGithubPersonalAccessToken();
         var githubClient = new GithubClient(_octoLogger, _clientFactory.CreateClient("Default"), _versionProvider, _retryPolicy, _dateTimeProvider, sourcePersonalAccessToken);
-        var multipartUploader = new ArchiveUploader(githubClient, uploadsUrl, _octoLogger, _retryPolicy);
+        var multipartUploader = new ArchiveUploader(githubClient, uploadsUrl, _octoLogger, _retryPolicy, _environmentVariableProvider);
         return new GithubApi(githubClient, apiUrl, _retryPolicy, multipartUploader);
     }
 
@@ -42,7 +42,7 @@ GithubApi ISourceGithubApiFactory.CreateClientNoSsl(string apiUrl, string upload
         uploadsUrl ??= DEFAULT_UPLOADS_URL;
         sourcePersonalAccessToken ??= _environmentVariableProvider.SourceGithubPersonalAccessToken();
         var githubClient = new GithubClient(_octoLogger, _clientFactory.CreateClient("NoSSL"), _versionProvider, _retryPolicy, _dateTimeProvider, sourcePersonalAccessToken);
-        var multipartUploader = new ArchiveUploader(githubClient, uploadsUrl, _octoLogger, _retryPolicy);
+        var multipartUploader = new ArchiveUploader(githubClient, uploadsUrl, _octoLogger, _retryPolicy, _environmentVariableProvider);
         return new GithubApi(githubClient, apiUrl, _retryPolicy, multipartUploader);
     }
 
@@ -52,7 +52,7 @@ GithubApi ITargetGithubApiFactory.Create(string apiUrl, string uploadsUrl, strin
         uploadsUrl ??= DEFAULT_UPLOADS_URL;
         targetPersonalAccessToken ??= _environmentVariableProvider.TargetGithubPersonalAccessToken();
         var githubClient = new GithubClient(_octoLogger, _clientFactory.CreateClient("Default"), _versionProvider, _retryPolicy, _dateTimeProvider, targetPersonalAccessToken);
-        var multipartUploader = new ArchiveUploader(githubClient, uploadsUrl, _octoLogger, _retryPolicy);
+        var multipartUploader = new ArchiveUploader(githubClient, uploadsUrl, _octoLogger, _retryPolicy, _environmentVariableProvider);
         return new GithubApi(githubClient, apiUrl, _retryPolicy, multipartUploader);
     }
 }
diff --git a/src/Octoshift/Services/ArchiveUploader.cs b/src/Octoshift/Services/ArchiveUploader.cs
index 23c4114b4..846e426ca 100644
--- a/src/Octoshift/Services/ArchiveUploader.cs
+++ b/src/Octoshift/Services/ArchiveUploader.cs
@@ -11,18 +11,26 @@ namespace OctoshiftCLI.Services;
 
 public class ArchiveUploader
 {
+    private const int BYTES_PER_MEBIBYTE = 1024 * 1024;
+    private const int MIN_MULTIPART_MEBIBYTES = 5; // 5 MiB minimum size for multipart upload. Don't allow overrides smaller than this.
+    private const int DEFAULT_MULTIPART_MEBIBYTES = 100;
+
     private readonly GithubClient _client;
     private readonly string _uploadsUrl;
     private readonly OctoLogger _log;
-    internal int _streamSizeLimit = 100 * 1024 * 1024; // 100 MiB
+    private readonly EnvironmentVariableProvider _environmentVariableProvider;
+    internal int _streamSizeLimit = DEFAULT_MULTIPART_MEBIBYTES * BYTES_PER_MEBIBYTE; // 100 MiB stored in bytes
     private readonly RetryPolicy _retryPolicy;
 
-    public ArchiveUploader(GithubClient client, string uploadsUrl, OctoLogger log, RetryPolicy retryPolicy)
+    public ArchiveUploader(GithubClient client, string uploadsUrl, OctoLogger log, RetryPolicy retryPolicy, EnvironmentVariableProvider environmentVariableProvider)
     {
         _client = client;
         _uploadsUrl = uploadsUrl;
         _log = log;
         _retryPolicy = retryPolicy;
+        _environmentVariableProvider = environmentVariableProvider;
+
+        SetStreamSizeLimitFromEnvironment();
     }
     public virtual async Task<string> Upload(Stream archiveContent, string archiveName, string orgDatabaseId)
     {
@@ -160,4 +168,23 @@ private Uri GetNextUrl(IEnumerable<KeyValuePair<string, IEnumerable<string>>> he
         }
         throw new OctoshiftCliException("Location header is missing in the response, unable to retrieve next URL for multipart upload.");
     }
+
+    private void SetStreamSizeLimitFromEnvironment()
+    {
+        var envValue = _environmentVariableProvider.GithubOwnedStorageMultipartMebibytes();
+        if (!int.TryParse(envValue, out var limitInMebibytes) || limitInMebibytes <= 0)
+        {
+            return;
+        }
+
+        if (limitInMebibytes < MIN_MULTIPART_MEBIBYTES)
+        {
+            _log.LogWarning($"GITHUB_OWNED_STORAGE_MULTIPART_MEBIBYTES is set to {limitInMebibytes} MiB, but the minimum value is {MIN_MULTIPART_MEBIBYTES} MiB. Using default value of {DEFAULT_MULTIPART_MEBIBYTES} MiB.");
+            return;
+        }
+
+        var limitBytes = (int)((long)limitInMebibytes * BYTES_PER_MEBIBYTE);
+        _streamSizeLimit = limitBytes;
+        _log.LogInformation($"Multipart upload part size set to {limitInMebibytes} MiB.");
+    }
 }
diff --git a/src/Octoshift/Services/EnvironmentVariableProvider.cs b/src/Octoshift/Services/EnvironmentVariableProvider.cs
index b68cbc4b7..e59b47109 100644
--- a/src/Octoshift/Services/EnvironmentVariableProvider.cs
+++ b/src/Octoshift/Services/EnvironmentVariableProvider.cs
@@ -18,6 +18,7 @@ public class EnvironmentVariableProvider
     private const string SMB_PASSWORD = "SMB_PASSWORD";
     private const string GEI_SKIP_STATUS_CHECK = "GEI_SKIP_STATUS_CHECK";
     private const string GEI_SKIP_VERSION_CHECK = "GEI_SKIP_VERSION_CHECK";
+    private const string GITHUB_OWNED_STORAGE_MULTIPART_MEBIBYTES = "GITHUB_OWNED_STORAGE_MULTIPART_MEBIBYTES";
 
     private readonly OctoLogger _logger;
 
@@ -65,6 +66,9 @@ public virtual string SkipStatusCheck(bool throwIfNotFound = false) =>
     public virtual string SkipVersionCheck(bool throwIfNotFound = false) =>
         GetValue(GEI_SKIP_VERSION_CHECK, throwIfNotFound);
 
+    public virtual string GithubOwnedStorageMultipartMebibytes(bool throwIfNotFound = false) =>
+        GetValue(GITHUB_OWNED_STORAGE_MULTIPART_MEBIBYTES, throwIfNotFound);
+
     private string GetValue(string name, bool throwIfNotFound)
     {
         var value = Environment.GetEnvironmentVariable(name);
diff --git a/src/OctoshiftCLI.IntegrationTests/BbsToGithub.cs b/src/OctoshiftCLI.IntegrationTests/BbsToGithub.cs
index 768ea5008..626a6dd04 100644
--- a/src/OctoshiftCLI.IntegrationTests/BbsToGithub.cs
+++ b/src/OctoshiftCLI.IntegrationTests/BbsToGithub.cs
@@ -60,7 +60,8 @@ public BbsToGithub(ITestOutputHelper output)
         _targetGithubHttpClient = new HttpClient();
         _targetGithubClient = new GithubClient(_logger, _targetGithubHttpClient, new VersionChecker(_versionClient, _logger), new RetryPolicy(_logger), new DateTimeProvider(), targetGithubToken);
         var retryPolicy = new RetryPolicy(_logger);
-        _archiveUploader = new ArchiveUploader(_targetGithubClient, UPLOADS_URL, _logger, retryPolicy);
+        var environmentVariableProvider = new EnvironmentVariableProvider(_logger);
+        _archiveUploader = new ArchiveUploader(_targetGithubClient, UPLOADS_URL, _logger, retryPolicy, environmentVariableProvider);
         _targetGithubApi = new GithubApi(_targetGithubClient, "https://api.github.com", new RetryPolicy(_logger), _archiveUploader);
 
         _blobServiceClient = new BlobServiceClient(_azureStorageConnectionString);
diff --git a/src/OctoshiftCLI.IntegrationTests/GhesToGithub.cs b/src/OctoshiftCLI.IntegrationTests/GhesToGithub.cs
index 59b7afbb6..d25cf21d2 100644
--- a/src/OctoshiftCLI.IntegrationTests/GhesToGithub.cs
+++ b/src/OctoshiftCLI.IntegrationTests/GhesToGithub.cs
@@ -49,10 +49,11 @@ public GhesToGithub(ITestOutputHelper output)
 
         _versionClient = new HttpClient();
         var retryPolicy = new RetryPolicy(logger);
-        _archiveUploader = new ArchiveUploader(_targetGithubClient, UPLOADS_URL, logger, retryPolicy);
+        var environmentVariableProvider = new EnvironmentVariableProvider(logger);
 
         _sourceGithubHttpClient = new HttpClient();
         _sourceGithubClient = new GithubClient(logger, _sourceGithubHttpClient, new VersionChecker(_versionClient, logger), new RetryPolicy(logger), new DateTimeProvider(), sourceGithubToken);
+        _archiveUploader = new ArchiveUploader(_targetGithubClient, UPLOADS_URL, logger, retryPolicy, environmentVariableProvider);
         _sourceGithubApi = new GithubApi(_sourceGithubClient, GHES_API_URL, new RetryPolicy(logger), _archiveUploader);
 
         _targetGithubHttpClient = new HttpClient();
diff --git a/src/OctoshiftCLI.Tests/Octoshift/Services/ArchiveUploadersTests.cs b/src/OctoshiftCLI.Tests/Octoshift/Services/ArchiveUploadersTests.cs
index 8f38370f1..b6676ce77 100644
--- a/src/OctoshiftCLI.Tests/Octoshift/Services/ArchiveUploadersTests.cs
+++ b/src/OctoshiftCLI.Tests/Octoshift/Services/ArchiveUploadersTests.cs
@@ -18,14 +18,16 @@ public class ArchiveUploaderTests
 
     private readonly Mock<GithubClient> _githubClientMock;
     private readonly Mock<OctoLogger> _logMock;
+    private readonly Mock<EnvironmentVariableProvider> _environmentVariableProviderMock;
     private readonly ArchiveUploader _archiveUploader;
 
     public ArchiveUploaderTests()
     {
         _logMock = TestHelpers.CreateMock<OctoLogger>();
         _githubClientMock = TestHelpers.CreateMock<GithubClient>();
+        _environmentVariableProviderMock = TestHelpers.CreateMock<EnvironmentVariableProvider>();
         var retryPolicy = new RetryPolicy(_logMock.Object) { _httpRetryInterval = 1, _retryInterval = 0 };
-        _archiveUploader = new ArchiveUploader(_githubClientMock.Object, UPLOADS_URL, _logMock.Object, retryPolicy);
+        _archiveUploader = new ArchiveUploader(_githubClientMock.Object, UPLOADS_URL, _logMock.Object, retryPolicy, _environmentVariableProviderMock.Object);
     }
 
     [Fact]
@@ -40,6 +42,176 @@ public async Task Upload_Should_Throw_ArgumentNullException_When_Archive_Content
         await Assert.ThrowsAsync<ArgumentNullException>(() => _archiveUploader.Upload(nullStream, archiveName, orgDatabaseId));
     }
 
+    [Fact]
+    public void Constructor_Should_Use_Valid_Environment_Variable_Value()
+    {
+        // Arrange
+        var customSizeMiB = 10; // 10 MiB
+        var customSizeBytes = customSizeMiB * 1024 * 1024;
+        var logMock = TestHelpers.CreateMock<OctoLogger>();
+        var environmentVariableProviderMock = TestHelpers.CreateMock<EnvironmentVariableProvider>();
+        var retryPolicy = new RetryPolicy(logMock.Object);
+
+        environmentVariableProviderMock
+            .Setup(x => x.GithubOwnedStorageMultipartMebibytes(false))
+            .Returns(customSizeMiB.ToString());
+
+        // Act
+        var archiveUploader = new ArchiveUploader(_githubClientMock.Object, UPLOADS_URL, logMock.Object, retryPolicy, environmentVariableProviderMock.Object);
+
+        // Assert
+        archiveUploader._streamSizeLimit.Should().Be(customSizeBytes);
+        logMock.Verify(x => x.LogInformation($"Multipart upload part size set to 10 MiB."), Times.Once);
+    }
+
+    [Fact]
+    public void Constructor_Should_Use_Default_When_Environment_Variable_Not_Set()
+    {
+        // Arrange
+        var defaultSize = 100 * 1024 * 1024; // 100 MiB
+        var logMock = TestHelpers.CreateMock<OctoLogger>();
+        var environmentVariableProviderMock = TestHelpers.CreateMock<EnvironmentVariableProvider>();
+        var retryPolicy = new RetryPolicy(logMock.Object);
+
+        environmentVariableProviderMock
+            .Setup(x => x.GithubOwnedStorageMultipartMebibytes(false))
+            .Returns(() => null);
+
+        // Act
+        var archiveUploader = new ArchiveUploader(_githubClientMock.Object, UPLOADS_URL, logMock.Object, retryPolicy, environmentVariableProviderMock.Object);
+
+        // Assert
+        archiveUploader._streamSizeLimit.Should().Be(defaultSize);
+    }
+
+    [Fact]
+    public void Constructor_Should_Use_Default_When_Environment_Variable_Is_Invalid()
+    {
+        // Arrange
+        var defaultSize = 100 * 1024 * 1024; // 100 MiB
+        var logMock = TestHelpers.CreateMock<OctoLogger>();
+        var environmentVariableProviderMock = TestHelpers.CreateMock<EnvironmentVariableProvider>();
+        var retryPolicy = new RetryPolicy(logMock.Object);
+
+        environmentVariableProviderMock
+            .Setup(x => x.GithubOwnedStorageMultipartMebibytes(false))
+            .Returns("invalid_value");
+
+        // Act
+        var archiveUploader = new ArchiveUploader(_githubClientMock.Object, UPLOADS_URL, logMock.Object, retryPolicy, environmentVariableProviderMock.Object);
+
+        // Assert
+        archiveUploader._streamSizeLimit.Should().Be(defaultSize);
+    }
+
+    [Fact]
+    public void Constructor_Should_Use_Default_When_Environment_Variable_Is_Zero()
+    {
+        // Arrange
+        var defaultSize = 100 * 1024 * 1024; // 100 MiB
+        var logMock = TestHelpers.CreateMock<OctoLogger>();
+        var environmentVariableProviderMock = TestHelpers.CreateMock<EnvironmentVariableProvider>();
+        var retryPolicy = new RetryPolicy(logMock.Object);
+
+        environmentVariableProviderMock
+            .Setup(x => x.GithubOwnedStorageMultipartMebibytes(false))
+            .Returns("0");
+
+        // Act
+        var archiveUploader = new ArchiveUploader(_githubClientMock.Object, UPLOADS_URL, logMock.Object, retryPolicy, environmentVariableProviderMock.Object);
+
+        // Assert
+        archiveUploader._streamSizeLimit.Should().Be(defaultSize);
+    }
+
+    [Fact]
+    public void Constructor_Should_Use_Default_When_Environment_Variable_Is_Negative()
+    {
+        // Arrange
+        var defaultSize = 100 * 1024 * 1024; // 100 MiB
+        var logMock = TestHelpers.CreateMock<OctoLogger>();
+        var environmentVariableProviderMock = TestHelpers.CreateMock<EnvironmentVariableProvider>();
+        var retryPolicy = new RetryPolicy(logMock.Object);
+
+        environmentVariableProviderMock
+            .Setup(x => x.GithubOwnedStorageMultipartMebibytes(false))
+            .Returns("-1000");
+
+        // Act
+        var archiveUploader = new ArchiveUploader(_githubClientMock.Object, UPLOADS_URL, logMock.Object, retryPolicy, environmentVariableProviderMock.Object);
+
+        // Assert
+        archiveUploader._streamSizeLimit.Should().Be(defaultSize);
+    }
+
+    [Fact]
+    public void Constructor_Should_Use_Default_And_Log_Warning_When_Environment_Variable_Below_Minimum()
+    {
+        // Arrange
+        var belowMinimumSizeMiB = 1; // below 5 MiB minimum
+        var defaultSizeMiB = 100;
+        var defaultSizeBytes = defaultSizeMiB * 1024 * 1024;
+        var minSizeMiB = 5; // 5 MiB minimum
+        var logMock = TestHelpers.CreateMock<OctoLogger>();
+        var environmentVariableProviderMock = TestHelpers.CreateMock<EnvironmentVariableProvider>();
+        var retryPolicy = new RetryPolicy(logMock.Object);
+
+        environmentVariableProviderMock
+            .Setup(x => x.GithubOwnedStorageMultipartMebibytes(false))
+            .Returns(belowMinimumSizeMiB.ToString());
+
+        // Act
+        var archiveUploader = new ArchiveUploader(_githubClientMock.Object, UPLOADS_URL, logMock.Object, retryPolicy, environmentVariableProviderMock.Object);
+
+        // Assert
+        archiveUploader._streamSizeLimit.Should().Be(defaultSizeBytes);
+        logMock.Verify(x => x.LogWarning($"GITHUB_OWNED_STORAGE_MULTIPART_MEBIBYTES is set to {belowMinimumSizeMiB} MiB, but the minimum value is {minSizeMiB} MiB. Using default value of {defaultSizeMiB} MiB."), Times.Once);
+    }
+
+    [Fact]
+    public void Constructor_Should_Accept_Value_Equal_To_Minimum()
+    {
+        // Arrange
+        var minimumSizeMiB = 5; // 5 MiB minimum
+        var minimumSizeBytes = minimumSizeMiB * 1024 * 1024;
+        var logMock = TestHelpers.CreateMock<OctoLogger>();
+        var environmentVariableProviderMock = TestHelpers.CreateMock<EnvironmentVariableProvider>();
+        var retryPolicy = new RetryPolicy(logMock.Object);
+
+        environmentVariableProviderMock
+            .Setup(x => x.GithubOwnedStorageMultipartMebibytes(false))
+            .Returns(minimumSizeMiB.ToString());
+
+        // Act
+        var archiveUploader = new ArchiveUploader(_githubClientMock.Object, UPLOADS_URL, logMock.Object, retryPolicy, environmentVariableProviderMock.Object);
+
+        // Assert
+        archiveUploader._streamSizeLimit.Should().Be(minimumSizeBytes);
+        logMock.Verify(x => x.LogInformation($"Multipart upload part size set to 5 MiB."), Times.Once);
+    }
+
+    [Fact]
+    public void Constructor_Should_Accept_Large_Valid_Value()
+    {
+        // Arrange
+        var largeSizeMiB = 500; // 500 MiB
+        var largeSizeBytes = largeSizeMiB * 1024 * 1024;
+        var logMock = TestHelpers.CreateMock<OctoLogger>();
+        var environmentVariableProviderMock = TestHelpers.CreateMock<EnvironmentVariableProvider>();
+        var retryPolicy = new RetryPolicy(logMock.Object);
+
+        environmentVariableProviderMock
+            .Setup(x => x.GithubOwnedStorageMultipartMebibytes(false))
+            .Returns(largeSizeMiB.ToString());
+
+        // Act
+        var archiveUploader = new ArchiveUploader(_githubClientMock.Object, UPLOADS_URL, logMock.Object, retryPolicy, environmentVariableProviderMock.Object);
+
+        // Assert
+        archiveUploader._streamSizeLimit.Should().Be(largeSizeBytes);
+        logMock.Verify(x => x.LogInformation($"Multipart upload part size set to 500 MiB."), Times.Once);
+    }
+
     [Fact]
     public async Task Upload_Should_Upload_All_Chunks_When_Stream_Exceeds_Limit()
     {
@@ -143,7 +315,7 @@ public async Task Upload_Should_Retry_Failed_Upload_Part_Patch_Requests()
         // Mocking the initial POST request to initiate multipart upload
         _githubClientMock
             .Setup(m => m.PostWithFullResponseAsync($"{baseUrl}{initialUploadUrl}", It.Is<object>(x => x.ToJson() == startUploadBody.ToJson()), null))
-            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", [firstUploadUrl]) }));
+            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", new[] { firstUploadUrl }) }));
 
         // Mocking PATCH requests for each part upload
         _githubClientMock // first PATCH request
@@ -151,12 +323,11 @@ public async Task Upload_Should_Retry_Failed_Upload_Part_Patch_Requests()
                 It.Is<HttpContent>(x => x.ReadAsByteArrayAsync().Result.ToJson() == new byte[] { 1, 2 }.ToJson()), null))
             .ThrowsAsync(new TimeoutException("The operation was canceled."))
             .ThrowsAsync(new TimeoutException("The operation was canceled."))
-            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", [secondUploadUrl]) }));
-
+            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", new[] { secondUploadUrl }) }));
         _githubClientMock // second PATCH request
             .Setup(m => m.PatchWithFullResponseAsync($"{baseUrl}{secondUploadUrl}",
                 It.Is<HttpContent>(x => x.ReadAsByteArrayAsync().Result.ToJson() == new byte[] { 3 }.ToJson()), null))
-            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", [lastUrl]) }));
+            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", new[] { lastUrl }) }));
 
         // Mocking the final PUT request to complete the multipart upload
         _githubClientMock
@@ -211,18 +382,18 @@ public async Task Upload_Should_Retry_Failed_Start_Upload_Post_Request()
             .SetupSequence(m => m.PostWithFullResponseAsync($"{baseUrl}{initialUploadUrl}", It.Is<object>(x => x.ToJson() == startUploadBody.ToJson()), null))
             .ThrowsAsync(new TimeoutException("The operation was canceled."))
             .ThrowsAsync(new TimeoutException("The operation was canceled."))
-            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", [firstUploadUrl]) }));
+            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", new[] { firstUploadUrl }) }));
 
         // Mocking PATCH requests for each part upload
         _githubClientMock // first PATCH request
             .Setup(m => m.PatchWithFullResponseAsync($"{baseUrl}{firstUploadUrl}",
                 It.Is<HttpContent>(x => x.ReadAsByteArrayAsync().Result.ToJson() == new byte[] { 1, 2 }.ToJson()), null))
-            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", [secondUploadUrl]) }));
+            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", new[] { secondUploadUrl }) }));
 
         _githubClientMock // second PATCH request
             .Setup(m => m.PatchWithFullResponseAsync($"{baseUrl}{secondUploadUrl}",
                 It.Is<HttpContent>(x => x.ReadAsByteArrayAsync().Result.ToJson() == new byte[] { 3 }.ToJson()), null))
-            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", [lastUrl]) }));
+            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", new[] { lastUrl }) }));
 
         // Mocking the final PUT request to complete the multipart upload
         _githubClientMock
@@ -275,18 +446,18 @@ public async Task Upload_Should_Retry_Failed_Complete_Upload_Put_Request()
         // Mocking the initial POST request to initiate multipart upload
         _githubClientMock
             .Setup(m => m.PostWithFullResponseAsync($"{baseUrl}{initialUploadUrl}", It.Is<object>(x => x.ToJson() == startUploadBody.ToJson()), null))
-            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", [firstUploadUrl]) }));
+            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", new[] { firstUploadUrl }) }));
 
         // Mocking PATCH requests for each part upload
         _githubClientMock // first PATCH request
             .Setup(m => m.PatchWithFullResponseAsync($"{baseUrl}{firstUploadUrl}",
                 It.Is<HttpContent>(x => x.ReadAsByteArrayAsync().Result.ToJson() == new byte[] { 1, 2 }.ToJson()), null))
-            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", [secondUploadUrl]) }));
+            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", new[] { secondUploadUrl }) }));
 
         _githubClientMock // second PATCH request
             .Setup(m => m.PatchWithFullResponseAsync($"{baseUrl}{secondUploadUrl}",
                 It.Is<HttpContent>(x => x.ReadAsByteArrayAsync().Result.ToJson() == new byte[] { 3 }.ToJson()), null))
-            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", [lastUrl]) }));
+            .ReturnsAsync((It.IsAny<string>(), new[] { new KeyValuePair<string, IEnumerable<string>>("Location", new[] { lastUrl }) }));
 
         // Mocking the final PUT request to complete the multipart upload
         _githubClientMock
diff --git a/src/OctoshiftCLI.Tests/Octoshift/Services/GithubApiTests.cs b/src/OctoshiftCLI.Tests/Octoshift/Services/GithubApiTests.cs
index f1027f1ac..a59e12729 100644
--- a/src/OctoshiftCLI.Tests/Octoshift/Services/GithubApiTests.cs
+++ b/src/OctoshiftCLI.Tests/Octoshift/Services/GithubApiTests.cs
@@ -18,7 +18,9 @@ namespace OctoshiftCLI.Tests.Octoshift.Services;
 public class GithubApiTests
 {
     private const string API_URL = "https://api.github.com";
+    private const string UPLOADS_URL = "https://uploads.github.com";
     private readonly RetryPolicy _retryPolicy = new(TestHelpers.CreateMock<OctoLogger>().Object) { _httpRetryInterval = 0, _retryInterval = 0 };
+    private readonly Mock<OctoLogger> _logMock = TestHelpers.CreateMock<OctoLogger>();
     private readonly Mock<GithubClient> _githubClientMock = TestHelpers.CreateMock<GithubClient>();
     private readonly Mock<ArchiveUploader> _archiveUploader;
 
@@ -46,7 +48,12 @@ public class GithubApiTests
 
     public GithubApiTests()
     {
-        _archiveUploader = TestHelpers.CreateMock<ArchiveUploader>();
+        _archiveUploader = new Mock<ArchiveUploader>(
+            _githubClientMock.Object,
+            UPLOADS_URL,
+            _logMock.Object,
+            _retryPolicy,
+            TestHelpers.CreateMock<EnvironmentVariableProvider>().Object);
         _githubApi = new GithubApi(_githubClientMock.Object, API_URL, _retryPolicy, _archiveUploader.Object);
     }
 
diff --git a/src/bbs2gh/Commands/GenerateScript/GenerateScriptCommand.cs b/src/bbs2gh/Commands/GenerateScript/GenerateScriptCommand.cs
index 5a09fcc84..d3af5da54 100644
--- a/src/bbs2gh/Commands/GenerateScript/GenerateScriptCommand.cs
+++ b/src/bbs2gh/Commands/GenerateScript/GenerateScriptCommand.cs
@@ -128,7 +128,8 @@ public GenerateScriptCommand() : base(
     public Option<bool> UseGithubStorage { get; } = new("--use-github-storage")
     {
         IsHidden = true,
-        Description = "Enables multipart uploads to a GitHub owned storage for use during migration",
+        Description = "Enables multipart uploads to a GitHub owned storage for use during migration. " +
+                      "Configure chunk size with the GITHUB_OWNED_STORAGE_MULTIPART_MEBIBYTES environment variable (default: 100 MiB, minimum: 5 MiB).",
     };
 
     public override GenerateScriptCommandHandler BuildHandler(GenerateScriptCommandArgs args, IServiceProvider sp)
diff --git a/src/bbs2gh/Commands/MigrateRepo/MigrateRepoCommand.cs b/src/bbs2gh/Commands/MigrateRepo/MigrateRepoCommand.cs
index bde333ff0..c93b5eaa9 100644
--- a/src/bbs2gh/Commands/MigrateRepo/MigrateRepoCommand.cs
+++ b/src/bbs2gh/Commands/MigrateRepo/MigrateRepoCommand.cs
@@ -201,7 +201,8 @@ public MigrateRepoCommand() : base(
                      "If your Bitbucket instance has a self-signed SSL certificate then setting this flag will allow the migration archive to be exported.");
     public Option<bool> UseGithubStorage { get; } = new(
         name: "--use-github-storage",
-        description: "Enables multipart uploads to a GitHub owned storage for use during migration")
+        description: "Enables multipart uploads to a GitHub owned storage for use during migration. " +
+                     "Configure chunk size with the GITHUB_OWNED_STORAGE_MULTIPART_MEBIBYTES environment variable (default: 100 MiB, minimum: 5 MiB).")
     { IsHidden = true };
 
     public override MigrateRepoCommandHandler BuildHandler(MigrateRepoCommandArgs args, IServiceProvider sp)
diff --git a/src/gei/Commands/GenerateScript/GenerateScriptCommand.cs b/src/gei/Commands/GenerateScript/GenerateScriptCommand.cs
index 40eb21187..d0e273948 100644
--- a/src/gei/Commands/GenerateScript/GenerateScriptCommand.cs
+++ b/src/gei/Commands/GenerateScript/GenerateScriptCommand.cs
@@ -108,7 +108,8 @@ public GenerateScriptCommand() : base(
         public Option<bool> UseGithubStorage { get; } = new("--use-github-storage")
         {
             IsHidden = true,
-            Description = "Enables multipart uploads to a GitHub owned storage for use during migration",
+            Description = "Enables multipart uploads to a GitHub owned storage for use during migration. " +
+                          "Configure chunk size with the GITHUB_OWNED_STORAGE_MULTIPART_MEBIBYTES environment variable (default: 100 MiB, minimum: 5 MiB).",
         };
 
         public override GenerateScriptCommandHandler BuildHandler(GenerateScriptCommandArgs args, IServiceProvider sp)
diff --git a/src/gei/Commands/MigrateRepo/MigrateRepoCommand.cs b/src/gei/Commands/MigrateRepo/MigrateRepoCommand.cs
index 514ae78bd..409dce2d5 100644
--- a/src/gei/Commands/MigrateRepo/MigrateRepoCommand.cs
+++ b/src/gei/Commands/MigrateRepo/MigrateRepoCommand.cs
@@ -109,7 +109,8 @@ public MigrateRepoCommand() : base(
         public Option<bool> UseGithubStorage { get; } = new("--use-github-storage")
         {
             IsHidden = true,
-            Description = "Enables multipart uploads to a GitHub owned storage for use during migration",
+            Description = "Enables multipart uploads to a GitHub owned storage for use during migration. " +
+                          "Configure chunk size with the GITHUB_OWNED_STORAGE_MULTIPART_MEBIBYTES environment variable (default: 100 MiB, minimum: 5 MiB).",
         };
 
         // Pre-uploaded archive urls, hidden by default