Connection error

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Hello,
Following the installation of Ultimate Member and when a user logs in, but not systematically and regardless of the internet browser used, the following message appears “An error has occurred, The page has probably been cached. Please try again”. and during the second connection attempt, it works, the connection to the account is effective.
Could you tell me if it is linked to a missing exception in where the problem comes from?
Thanks in advance
Site: cgvvr.org

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