What does Windows error code 688 (ERROR_DBG_EXCEPTION_NOT_HANDLED) mean?

ERROR_DBG_EXCEPTION_NOT_HANDLED

What ERROR_DBG_EXCEPTION_NOT_HANDLED means

A debugger received an exception notification but did not report the exception as handled. In practical terms, this status belongs to native debugging and exception dispatch: a debugger event loop returns a continue status that allows normal exception processing to resume.

Typical causes

• The debugger deliberately passed a first-chance exception back to the debuggee
• A debugger extension or automation layer used the wrong continuation code
• The exception was expected by the runtime but not recognized by the attached debugger

How to investigate

1. Record the exception code, address, first-chance flag, thread identifier, and continuation status
2. Check which component called ContinueDebugEvent and which status it supplied
3. Reproduce without debugger extensions to separate debugger policy from application failure

Developer guidance

Treat this value as part of the debugger protocol, not automatically as the root application error. Preserve the original exception record because it explains what the debuggee actually raised.

References

• Microsoft: System error codes 500–999