After a reboot of both the primary hub and UMP robot, the UMP USM portlet fails to load and we see the following error before the USM portlet enters a loading state which never finishes:
An unknown error has occurred.
Refreshing your browser may resolve the issue.
Details: com.firehunter.ump.exceptions.DataFactoryException : com.firehunter.ump.exceptions.DataFactoryException: Column 'CM_CONFIG_ITEM_TO_MASTER.master_id' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause. Please check the log for more information.
UIM Server / UMP 8.51
The disk on the UIM Primary hub where the UIM Server was installed had ~300M free.
In this case, the disk space was consumed by files in the debug directory of the 8.65HF1 version of the spectrumgtw probe.
Freed up ~18G of disk space by deleting the debug directory of the spectrumgtw probe, upgrading the spectrumgtw probe to 8.65HF2, then restarting the primary hub followed by restarting the UMP robot.