BUG: Nextcloud becomes unavailable shortly after successful app updates

Nextcloud: 34.0.2
PHP: 8.4.16.

Description

A Nextcloud instance became unavailable a few seconds after one or more applications had been updated successfully. The update operation itself completed without a visible error. Subsequent requests failed with an HTTP 502 Bad Gateway response. An emergency redeployment restored the service. The updated applications remained installed after the redeployment, and Nextcloud operated normally again.

Observed sequence

Updates were installed through Nextcloud. Nextcloud reported that the updates had completed successfully. A few seconds later, the instance stopped responding to web requests. The reverse proxy subsequently returned HTTP 502 Bad Gateway. Container got redeployed, after which the instance became available again. This sequence describes the observed incident, and occurs every time

Expected behavior

Nextcloud remains available after successful application updates. The application updates should not interrupt subsequent web requests.

Actual behavior

Nextcloud became unavailable shortly after the updates. Subsequent requests returned HTTP 502 Bad Gateway until the container was redeployed.

No files or tests are named. Start by reproducing the reported sequence on Nextcloud 34.0.2 with PHP 8.4.16: complete an in-app application update, then observe the container and subsequent requests through the reverse proxy. Done means successful updates no longer lead to HTTP 502 responses or require container redeployment.