Can't save worlds

[dawidg81]

When I do /save, this error occurs:

[17:22:33][ERROR][WORLD-SAVE]: Error While Saving World default - ValueError: truncate of closed file
Traceback (most recent call last):
  File "D:\classicv\obsidian\player.py", line 804, in handlePlayerCommand
    await command.execute(self, *parsedArguments, **parsedKwArgs)
  File "D:\classicv\obsidian\modules\essentials.py", line 1646, in execute
    ctx.worldPlayerManager.world.worldManager.saveWorlds()
  File "D:\classicv\obsidian\world.py", line 335, in saveWorlds
    raise MapSaveError("Error Occurred During World Save! Check Logs For More Info!")
obsidian.errors.MapSaveError: Error Occurred During World Save! Check Logs For More Info!

[17:22:34][ERROR][COMMAND]: Command SaveWorlds Raised An Error! Error Occurred During World Save! Check Logs For More Info!
[17:22:34][DEBUG][PLAYER-MESSAGE]: Sending Player dawidg81 Message &cAn Unknown Internal Server Error Has Occurred!

The similar issue with /saveworld :

[17:25:13][CHAT][WORLD][DEFAULT]: &aStarting Manual World Save!
[17:25:13][LOG][WORLD-SAVE]: Attempting To Save World default
[17:25:13][DEBUG][WORLD-SAVE]: Creating Temporary Backup Of World default
[17:25:13][WARN][WORLD-SAVE]: Backup File Already Exists For World default.
[17:25:13][WARN][WORLD-SAVE]: This usually means there was an unclean previous save.
[17:25:13][DEBUG][OBSIDIANWORLD]: Saving Metadata
[17:25:13][DEBUG][OBSIDIANWORLD]: Saving Additional Metadata
Traceback (most recent call last):
  File "D:\classicv\obsidian\player.py", line 804, in handlePlayerCommand
    await command.execute(self, *parsedArguments, **parsedKwArgs)
  File "D:\classicv\obsidian\modules\essentials.py", line 1670, in execute
    world.saveMap()
  File "D:\classicv\obsidian\world.py", line 693, in saveMap
    self.worldManager.worldFormat.saveWorld(self, self.fileIO, self.worldManager)
  File "D:\classicv\obsidian\modules\core.py", line 1090, in saveWorld
    fileIO.truncate(0)
ValueError: truncate of closed file

[17:25:13][ERROR][COMMAND]: Command SaveWorld Raised An Error! truncate of closed file
[17:25:13][DEBUG][PLAYER-MESSAGE]: Sending Player dawidg81 Message &cAn Unknown Internal Server Error Has Occurred!

I tried fixing it by myself, but nothing really worked.