One of our validator has been disputed exact at same time when we were upgrading client.

Bellow some details:
12:22 - 12:25 UTC We were upgrading client from 0.9.28 to 0.9.29

Validator:15qomv8YFTpHrbiJKicP4oXfxRDyG4XEHZH7jdfJScnw2xnV
Event: ParasDisputes (https://polkadot.subscan.io/extrinsic/12059266-1)
Epoch: 5051
Block:12059266

Upgrade was by ansible, task steps:

1. stop node through systemd(SIGTERM)
2. Download and replace new version
3. Safe start(will start if finalized block grew up at least 3 in 30 seconds)

Setup:
VM instance hosted in GCP - instance_type: c2d-highcpu-8, min_cpu_platform: "AMD Milan"
DB: RocksDB, pruned
PVF execution time <= 1s 100%

Events before stop:

2022-09-15 12:22:01 Detected invalid candidate as an approval checker. reason=ExecutionError("ambiguous worker death") candidate_hash=0xa2cfd2254a71c3d5e218d51cb7bb4e310d381049916350a7adabe5bcd4545972 para_id=Id(2030) traceID=216414003027371284759400717824118443569

2022-09-15 12:22:01 subsystem exited with error subsystem="approval-voting-subsystem" err=FromOrigin { origin: "approval-voting", source: Generated(TaskSpawn("get-approval-signatures")) }

2022-09-15 12:22:01 failed to send an execute request worker_pid=719645 validation_code_hash=0x5fb733293d5dc16e5a7c3daa1d504f0518fb0e3d1556f12be497df4d40030db4 error=Os { code: 32, kind: BrokenPipe, message: "Broken pipe" }