Recently we have been noticing the following type of errors in the application-s

Recently we have been noticing the following type of errors in the application-server.log file "Unable to acquire a Read connection..." and "Unable to acquire a Write connection...". This type of errors only appear in our Appian 7.3 PROD environment. The ones related to "evaluating expression" are more critical because they would stop the node execution and process flow, we need to manually restart the node to continue the process instance flow. Below is the error details:

Details: ERROR:An error occurred while evaluating expression: SigImagesDocument : if ( pv!apr_super_index > 0 , if ( isnull ( #"0000cd79-25d0-8000-73cd-0a000064044c" ( pv!apr_users [ pv!apr_super_index ] ) ) ,
append ( pv!SigImagesDocument , #"0000cd79-3ecd-8000-73cd-0a000064044c" ) , append ( pv!SigImagesDocument , #"0000cd79-25d0-8000-73cd-0a000064044c" ( pv!apr_users [ pv!apr_super_index ] ) ) ) , pv!SigImagesDocument )
(Expression evaluation error in rule 'getdocumentid'...

OriginalPostID-156980

OriginalPostID-156980