Candlepin fails to start with "ERROR: could not read block [...] in file: read only 0 of 8192 bytes" in Red Hat Satellite 6

Issue

• Accessing Sync Plans, Manifest Refresh, or other subscription-related pages in the Satellite WebUI fails with Oops, we're sorry but something went wrong or Katello::Errors::CandlepinNotRunning.

• Running hammer ping reports FAIL status for candlepin, candlepin_auth, and candlepin_events:

  candlepin:
      Status:          FAIL
      Server Response: Message: 404 Not Found
  candlepin_auth:
      Status:          FAIL
      Server Response: Message: Katello::Errors::CandlepinNotRunning
  candlepin_events:
      Status:          FAIL
      message:         Not running
      Server Response: Duration: 0ms
  

  • In /var/log/candlepin/error.log, the following error is seen during startup:

  2026-01-29 09:13:55,719 [thread=main] [=, org=, csid=] ERROR org.candlepin.async.JobManager - Unexpected exception occurred while starting job manager
  Caused by: org.quartz.JobPersistenceException: Couldn't recover jobs: ERROR: could not read block 9 in file "base/16385/19631": read only 0 of 8192 bytes
  Caused by: org.postgresql.util.PSQLException: ERROR: could not read block 9 in file "base/16385/19631": read only 0 of 8192 bytes
  at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2733)
  java.lang.NoClassDefFoundError: io/netty/channel/ServerChannelRecvByteBufAllocator$1