How did I fix «An error has happened during application run» in Magento 2.3.7 and 2.4.4 backend?

Issues
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1

magento.stackexchange.com/questions/357419

2

The internal error is «strtotime() expects parameter 1 to be string, null given in vendor/magento/module-security/Model/AdminSessionInfo.php:136».
I have published the solution there.