MOM can run out of memory while processing user/user groups related reports. The out of memory exception usually happens when number of user/user groups for Business Applications in Enterprise mode is close to or exceeds maximum settings (i.e. 50,000 users, 10,000 user groups). OOM can occur for both scheduled and manually created reports.
The MOM crashes and does not recover.
Increase the Java heap size for the MOM. At least 6-8GB for the MOM is recommended. But if this issue occurs, then the heap size needs to be increased.