Upgrade from 7.12.8 to 7.14.6 Failed – strftime() Deprecated Error

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Blank login page after update 7.13 to 7.14 , repair, log out and log in

Turn off display_errors in your php.ini and restart web server. Errors should not appear on screen, only in the logs. “Deprecated” errors are nothing to worry about, they are messages for future developers, not errors for present users.

Cannot add, see details, or change contacts since migration to 8.7

Anyways these errors look deprecated. Maybe you need to update your php.ini file error_reporting=E_ALL & ~E_DEPRECATED & ~E_STRICT Then restart PHP.