Debugging

All mod output lands in one place: python.log at the root of your game installation. Every print statement, every unhandled exception, and every loader message ends up there.

Reading python.log

C:\Games\World_of_Tanks_EU\python.log

Each line follows the format DATE TIME: LEVEL: Main: MESSAGE. For your mods, look for lines with your TAG:

2026-01-15 12:34:56.123: INFO:  Main: [my_mod] loaded
2026-01-15 12:35:02.456: INFO:  Main: [my_mod] tank: AMX 50 B
2026-01-15 12:39:14.789: ERROR: Main: Traceback (most recent call last):
  ...

Open it in a text editor that supports live reload (VS Code, Notepad++) so it updates as you play. Search for your TAG to filter out engine noise.

Before launching: py_compile

Always compile before testing. py_compile catches syntax errors immediately without having to launch the game:

"C:\Python27\python.exe" -m py_compile mod_my_mod.py

A syntax error prints directly to the terminal:

  File "mod_my_mod.py", line 12
    def fini()
             ^
SyntaxError: invalid syntax

No output means the file compiled cleanly.

Runtime exceptions

When a mod throws an unhandled exception, the traceback appears in python.log under ERROR: Main:. The game continues running but the mod is disabled for that session.

2026-01-15 12:34:56.123: ERROR: Main: Traceback (most recent call last):
  File "scripts/client/gui/mods/mod_my_mod.py", line 8, in init
    g_playerEvents.onAccountBecomePlayerr += _onAccountBecomePlayer
AttributeError: 'Event' object has no attribute 'onAccountBecomePlayerr'

Read from the bottom up: the last line tells you what went wrong, the lines above show where.

Common errors

ImportError

ImportError: No module named gui.Scaleform.daapi.view.battle.shared.damage_panell

A wrong module path. Look up the exact path in wgmods-dev/wot-src under scripts/client/.

AttributeError

AttributeError: 'VehicleType' object has no attribute 'classTag'

A wrong property or method name. Check the class in wot-src to find the correct attribute.

TypeError

TypeError: _patched() takes exactly 2 arguments (1 given)

A method patch with the wrong signature. Instance methods always receive self as the first argument:

# Wrong
def _patched(health):
    pass

# Correct
def _patched(self, health):
    pass

Mod loads but nothing happens

If you see loaded in python.log but your callback never fires:

• Wrong event name: double-check the spelling against the client architecture reference.
• Subscribed too early: some events require the object to exist first. For example, player.arena signals must be subscribed in onAvatarReady, not in init().
• Stale .pyc: the game loads the .pyc, not the .py. Recompile after every change.
• Missing mod_ prefix: files without the mod_ prefix are silently ignored by the mod loader.

Visual debugging

For values that change during a session, print to python.log is most practical. For real-time feedback in the hangar, SystemMessages.pushMessage surfaces the value as an in-game notification without leaving the client:

import gui.SystemMessages as SystemMessages
from gui.SystemMessages import SM_TYPE

SystemMessages.pushMessage('[my_mod] value: ' + str(value), type=SM_TYPE.Information)

Use SM_TYPE.Warning (orange) to make debug messages visually distinct from normal notifications.