Why does SAPInstance/SAPDatabase cluster resource fail to start/stop?

Issue

• rgmanager is unable to start or stop a SAPInstance and/or SAPDatabase cluster resource
• The following messages are seen in the logs:

rgmanager[45629]: [SAPInstance] sapstartsrv is not running for instance SID-ASCS00, it will be started now
rgmanager[45687]: [SAPInstance] found valid open file descriptors limit at /usr/sap/sapservices: , applying...
rgmanager[45737]: [SAPInstance] found valid stack size limit at /usr/sap/sapservices: , applying...
rgmanager[45787]: [SAPInstance] found valid process data segment size limit at /usr/sap/sapservices: , applying...
rgmanager[45841]: [SAPInstance] sapstartsrv for instance SID-ASCS00 could not be started!
rgmanager[45883]: [SAPInstance] SAP Instance SID-ASCS00 stop failed: 
...
rgmanager[43818]: stop on SAPInstance "SID_ASCS00_orasapa3p" returned 1 (generic error)
rgmanager[49257]: [SAPDatabase] Failed to stop database, return code 1
rgmanager[49279]: [SAPDatabase] SAP database SID stop failed: <err> Failed to stop database, return code 1
rgmanager[49311]: [SAPDatabase] listener process not running for LISTENER for SID
rgmanager[43818]: stop on SAPDatabase "SID" returned 1 (generic error)