MUTEX_ALREADY_OWNED (0xBF)
What is this error?
A thread attempted to acquire a mutex that it already owns. This is a driver logic error indicating a recursive lock attempt.
Common causes
- driver logic error
- recursive function acquiring same mutex
- third-party driver bug
How to fix it
- Identify faulting driver from minidump
- update or remove it
Too many steps? Crashless can diagnose this automatically — checks your drivers, temps, VRAM, and 400+ known error patterns.
Get free AI diagnosis Detailed analysis
Bug check 0x000000BF (MUTEX_ALREADY_OWNED) occurs when a thread tries to acquire a mutex (mutual exclusion lock) that it already holds. This is always a driver logic error — the driver has a code path that recursively tries to acquire the same lock, causing a deadlock. The minidump will clearly identify the faulting driver. Fixes:
- Check the minidump for the faulting driver,
- Update the driver to the latest version (the bug may be fixed),
- If no update available: contact the driver vendor to report the bug,
- As a workaround: if the driver is optional (e.g., a peripheral driver), uninstall it.
When to seek help
If this error keeps happening after trying the fixes above, it may point to a deeper hardware or system issue. Consider professional help if:
- The crash occurs across multiple games or applications
- You see the same error after a clean Windows install
- Your PC is less than a year old (could be a warranty issue)
- You smell burning or hear unusual sounds from your PC
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