I have the following error code in many task of my Elgg site.

An unrecoverable error has occurred and has been logged. Contact the site administrator with the following information:

Exception at time 1543956666.

For exemple, when I send a private message to a user. Also wnen I accept a user demand to joint on a groupe. The same message appear for the user who ask to joint a groupe.

Some one know how I can fixe this?

Thank you for your time