nova conductor/scheduler no valid hosts found errors are difficult to understand

Solution Verified - Updated -


  • The nova conductor log only says No valid host found, but doesn't give any reason why. Enabling debug and verbose logging (in older releases - see example #4 for OSP 16.x) doesn't help.
  • Is there a way to make the No valid host found messages give the real reason for failure?
  • How does one understand or troubleshoot the No valid host found error in nova-conductor or nova-scheduler logs?
  • This log message doesn't give very informative details on what the failure was:
    NoValidHost: No valid host was found. There are not enough hosts available.


  • Red Hat OpenStack Platform 16.x
  • Red Hat OpenStack Platform 10
  • Red Hat OpenStack Platform 9
  • Red Hat OpenStack Platform 8
  • Red Hat OpenStack Platform 7

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