ESP32 CYD 2432S028 SdFat - File system is not mounted

[bettellam]

Good morning, in my project with the ESP32 CYD (GNSS NTRIP MANAGER), I couldn't use simpleFtpServer. Since I'm not an expert programmer, after countless attempts, I asked Claude AI for help, and finally everything worked.
After completing my tests, I had ClaudeAI write this issue:

DEFAULT_STORAGE_TYPE_ESP32 cannot be overridden from sketch — must edit FtpServerKey.h directly

Environment

• Library: SimpleFTPServer 3.0.2
• Platform: ESP32 (esp32 Arduino core 3.3.6, ESP-IDF 5.5.2)
• Storage: SdFat2 (SdFat object)
• Network: WiFi AP mode

Problem

The documentation and header comments suggest that DEFAULT_STORAGE_TYPE_ESP32 can be overridden before including the library:

#undef  DEFAULT_STORAGE_TYPE_ESP32
#define DEFAULT_STORAGE_TYPE_ESP32 STORAGE_SDFAT2
#include <FtpServer.h>

This compiles without errors, but at runtime the FTP server fails with:

FTP: Connected!
[E][vfs_api.cpp:26] open(): File system is not mounted

The root cause is that Arduino IDE compiles libraries as separate translation units. Any #define placed in the sketch (.ino) is not visible to FtpServer.cpp during its compilation. As a result, FtpServer.cpp always sees the default value (STORAGE_FFAT) defined in FtpServerKey.h, regardless of what the sketch defines.

The only working solution is to edit FtpServerKey.h directly:

#ifndef DEFAULT_FTP_SERVER_NETWORK_TYPE_ESP32
    #define DEFAULT_FTP_SERVER_NETWORK_TYPE_ESP32  NETWORK_ESP32
    #define DEFAULT_STORAGE_TYPE_ESP32             STORAGE_SDFAT2  // changed from STORAGE_FFAT
#endif

Suggested fix

Consider supporting a project-level configuration file (e.g. FtpServerUser.h) that is included by FtpServerKey.h when present, following the same pattern used by libraries like TFT_eSPI (User_Setup.h). This would allow per-project configuration without modifying library files.

Alternatively, document clearly that sketch-level overrides do not work for this library and that FtpServerKey.h must be edited directly.