3660062 - PI/PO Sender File interfaces not polling files from source directory

• The Process Integration (PI) or Process Orchestration (PO) File Sender Adapter stops polling files from source directory or directories. 
• The system has been updated to SP28 or higher.
• The system is using an ABAP Data source in the UME.
• In the defaultTrace files, exceptions similar to the below are found:
  #2.0#2025 09 08 13:31:38:317#+0200#Error#com.sap.engine.core.thread.impl3.SingleThread#com.sap.ASJ.krn_thd.000003#BC-XI#com.sap.aii.af.lib#C0000AB9DA208C1E0000000400001TJ6#2895950000002812~com.sap.engine.core.thread.impl3.SingleThread#Guest#0#8F0684AD79F311F08C60E8990ZW9DA20#8f0684ad79f897v08c60e8990ab9da20~0#SAP_AFScheduler.Worker#Plain~
  Execution of Runnable [com.sap.aii.af.lib.scheduler.JobBroker$Worker@53240186] throws the following Exception [com.sap.aii.af.utilxi.PrivilegedActionHelperException: com.sap.security.api.NoSuchUserException: USER_AUTH_FAILED: User account for logonid "PIAF<SID>" not found!].
  [EXCEPTION]
  com.sap.aii.af.utilxi.PrivilegedActionHelperException: com.sap.security.api.NoSuchUserException: USER_AUTH_FAILED: User account for logonid "PIAF<SID>" not found!
  at com.sap.aii.af.utilxi.PrivilegedActionExecutor.executePrivilegedAction(PrivilegedActionExecutor.java:105)
  
  Preceded by:
  2.0#2025 09 08 13:30:59:168#+0200#Error#com.sap.security.core.persistence.datasource.imp.R3Persistence#com.sap.ASJ.umecore.000016#BC-JAS-SEC-
  UME#com.sap.security.core.sda#C0000AB9DA207DD00000000300016P59#2895953000002779~com.sap.security.core.persistence.datasource.imp.R3Persistence#Guest#0~5234267B914811F08529C0B10AB9DA20#5234267b68421f08529c0b10ab9da20~0#SAP_AFScheduler.Worker#Plain#
  An exception was thrown in the UME/ABAP user management connector that was caused by unavailability of the RFC communication with the backend system: "com.sap.conn.jco.JCoException: (106) JCO_ERROR_RESOURCE: Connection pool

SAP NetWeaver 7.5

Process Orchestration 7.50, PI 7.50, PO 7.50, NetWeaver, XI, clusterSyncMode, polling, poling, lock, process, folder, not picking, picking, communication channel, directory, source, rwb, pimon, communication channel monitoring, communication channel monitor, server nodes, multiple, enqueue service, channel, channels, pi monitor, datasource , KBA , BC-XI-CON-FIL , File Adapter , BC-XI-CON-AFW-SCH , Job Scheduler , Problem