This issue can be caused by the upgrade failing to remove legacy Java files located in (InstallLocation)\Deep Security Manager\webclient\webapps\ROOT\WEB-INF\lib folder.

To confirm the cause of the issue, check the following:

1. Access the location (InstallLocation)\Deep Security Manager\webclient\webapps\ROOT\WEB-INF\lib folder on your Deep Security Manager machine.
2. Check the directory for .jar files that have a Last Write Time that is not the latest and have a similar name, but with later build versions to current files.

   For example, for an upgrade performed on October 17, 2018, the directory shows the following:

   Mode                LastWriteTime     Length Name 
                -----        12.10.2017     15:11      14766 aopalliance-repackaged-2.4.0-b34.jar 
                                            -a---        17.10.2018     15:20      14768 aopalliance-repackaged-2.5.0-b32.jar  
       -----        12.10.2017     15:11     107434 aspectjrt-1.8.2-sources.jar           
                                           -a---        17.10.2018     15:19     117099 aspectjrt-1.8.2.jar       
       -a---        17.10.2018     15:19   59168799 aws-java-sdk-1.11.126.jar  
                                                      -----        12.10.2017     15:11   49753103 aws-java-sdk-1.11.80.jar

   Any files dated October 12, 2017 are older versions and can be removed.

To resolve the issue, remove the older versions of Java files:

1. Back up the (InstallLocation)\Deep Security Manager\webclient\webapps\ROOT\WEB-INF\lib folder.
2. Stop the Deep Security Manager service, if running.
3. Delete any .jar files that are present in that location that have an older date as identified from previous checking.
4. Run the Deep Security Manager installer again and select the Repair option.
5. Wait for the repair to complete.
6. Once completed, verify the Deep Security Manager service is started. Otherwise, start the service.
7. Access the Deep Security Manager console.