Couldn't login to Applications Manager plugin / Managed server to Admin server sync is not working in plugin

Couldn't login to Applications Manager plugin / Managed server to Admin server sync is not working in plugin

1. PostgreSQL might have reached maximum connection count
 If the product is using PostgreSQL as the backend database, please check the latest log file from the <OPM_Home>\OpManager\pgsql\data\'pg_log' for the below print.
org.postgresql.util.PSQLException: FATAL: remaining connection slots are reserved for non-replication superuser connections

If this trace is found with a recent timestamp, follow the below steps to resolve this,

  1. Open postgresql.conf under <OPM_Home>\OpManager\pgsql\data
  2. Search using the keyword max_connections
  3. If the line starts with # i.e. #max_connections = 100, please remove to uncomment the line
  4. Increase the value from 100 to 200 i.e. max_connections = 200
  5. Properly restart the OpManager service  
2. License count might have been exceeded 
  1. Copy Rest API key of the particular user in OpManager by going to Settings -> Rest API
  2. Access Applications Manager plugin in a separate tab
  3. Provide the user name and API Key (copied in first point) as password
  4. If license count exceeded page is shown, please check and unmanage the extra montiors/Add-Ons that is currently violating the license
  5. Once the extra monitors are unmanaged, Applications Manager auto-login will work properly