Timesheet viewing problem for non admin user on Redmin new version

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We just upgraded Redmine 4.7 to Redmine 5.1.1.stable.
Everything is working correctly except a non-admin user cannot view the timesheet.. at all.

It creates a "Redmine 500 error":

'''
Internal error
An error occurred on the page you were trying to access.
If you continue to experience problems please contact your Redmine administrator for assistance.

If you are the Redmine administrator, check your log files for details about the error.

Back

'''