You can enable service tracing and recording a trace log as explained in the following KB article:
After you make the necessary changes to the webconfig file, reproduce the issue and any exceptions will be caught in a log file, saved in the root of the project.
Additionally you can remove all files in the App_Data/Sitefinity/Logs folder, log in the backend administration and try to remove an event. All exceptions and stack traces will be recorded in a new Error.log file.
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