In Adobe Journey Optimizer, the “INTERNAL” error usually indicates a server-side issue.
https://experienceleaguecommunities.adobe.com/t5/journey-optimizer-questions/internal-server-error-cjmt-000001-500/m-p/626268
It could be due to a variety of reasons such as issues with the server, problems with the configuration, or errors in the journey setup.
Check : https://experienceleague.adobe.com/docs/journey-optimizer/using/orchestrate-journeys/manage-journey/troubleshooting.html?lang=en
The “messageExecutionFailed” error typically occurs when there’s an issue with the execution of a message in a journey. This could be due to problems with the message configuration, issues with the data used in the message, or errors in the journey setup.
As for the issue of more profiles exiting the journey than entering, it could be due to the re-entrance settings of your journey. In Adobe Journey Optimizer, a profile cannot be present multiple times in the same journey at the same time. However, if re-entrance is enabled, a profile can enter a journey several times, but cannot do it until they fully exited the previous instance of the journey.
https://experienceleague.adobe.com/docs/journey-optimizer/using/orchestrate-journeys/manage-journey/entry-management.html?lang=en
If more profiles are exiting than entering, it might be that some profiles are re-entering the journey.
