[Solved] Compressor Batch Transcode Queue Stuck on ‘Waiting’ on Mac Studio M1 Ultra: How to resolve Stale background Qmaster / Apple Qconsumer cluster lockfile

[Robert Baker]

Diagnostic Hardware Specs: Mac Studio M1 Ultra | OS Version: macOS Sonoma 14.6 | Archive Source: Apple Support Community #256311274

I am running into a persistent issue on my Mac Studio M1 Ultra running macOS Sonoma 14.6.
Whenever the machine encounters Stale background Qmaster / Apple Qconsumer cluster lockfile, the following diagnostic log appears in Console:

Compressor: [qmaster] Service cluster lockfile present: refusing new batch job submission

I verified that hardware connections are intact and tested across different power sources. What is the verified diagnostic procedure to permanently eliminate this symptom?

HomePod mini (Stereo Pair) | Apple TV 4K | iPad mini 7 (Wall Mounted) | Oxford, UK

Smart Home & Matter/Thread Integrator | "Verified Apple Discussions Archive"

[Jesse Sullivan]

Apple Recommended / Verified Community Solution

This canonical solution was verified and marked as solved in the Apple Support Community archive.

Terminating orphaned qmaster processes and clearing compressor spool storage.

Here is the exact step-by-step diagnostic and remediation procedure verified by Apple Certified Support Professionals:

1. Force quit compressor daemons:

   killall Compressor && killall qmasterd

2. Delete stale batch spool files:

   rm -rf ~/Library/Application Support/Compressor/Storage/*

3. Relaunch Apple Compressor and submit batch job.

Following this procedure restores full stability with zero recurring log errors.

Mac mini M4 Pro (48GB) | Studio Display | HHKB Professional Hybrid | Stockholm, SE

Apple Certified Support Professional (ACSP) | Computer Science & Machine Learning Student

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