Unable to access Backup Manager in Plesk: 504 Gateway Timeout

Symptoms

• Unable to access Plesk > Tools & Settings > Backup Manager, the following error is shown in browser:

  CONFIG_TEXT: 504 Gateway Timeout

• There are the following records in /var/log/sw-cp-server/error_log file:

  CONFIG_TEXT: [error] 3235#0: *1483 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 123.123.123.12, server: , request: "GET /plesk/server/backup/local-repository/ HTTP/1.1", upstream: "fastcgi://unix:/var/run/sw-engine.sock", host: "11.12.13.14:8443", referrer: "https://11.12.13.14:8443/admin/server/tools?context=tools"

• It is possible to find such system process while trying to access Backup Manager:

  # ps ax | grep pmm
  11357 ? R 0:37 /usr/bin/python /usr/local/psa/admin/sbin/pmmcli --get-tasks-list Restore,Backup 5dfb2ce3-1743-4cac-902e-78773bc245d6 any

• There are a lot of "Permission denied" messages in /usr/local/psa/PMM/sessions/TIME_STAMP/migration.result files:

  # egrep -lir 'Permission denied' /usr/local/psa/PMM/sessions/ | xargs wc -l
  34544 /usr/local/psa/PMM/sessions/2013-11-13-030003.384/migration.result
  34544 /usr/local/psa/PMM/sessions/2013-12-22-013005.54/migration.result
  34543 /usr/local/psa/PMM/sessions/2013-12-05-013004.227/migration.result
  34534 /usr/local/psa/PMM/sessions/2013-11-06-030003.347/migration.result
  35502 /usr/local/psa/PMM/sessions/2013-11-10-030003.623/migration.result

Cause

Resolution