The CEM Admin Console which was initially working fine after a recent upgrade from APM 9.7 to APM 10.3, has suddenly became inaccessible with the following error:
Problem accessing /. Reason:
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Basically, the error indicates some jar files required to load the CEM Administration Console were missing. In this case, it was determined that when the database upgrade was being performed on the Secondary MOM, the Database Upgrade option was selected, in which the upgrade installer proceeded to install files required particularly for this option, and removed other existing files that was not included for this option from the shared install directory. This has resulted in the CEM console not able to load successfully due to the missing/removed files.
APM 10.3 with shared install directory for Primary & Secondary MOMs
Re-running the database upgrade steps and selecting the Enterprise Manager & WebView options ensured all existing files are installed/not removed from the shared install directory, while the database upgrade is being done.
Please refer to TEC1171416 for best practice when running a custom APM installation.