Error : rtrim() expects parameter 1 to be string, bool given#0 ./vendor/magento/framework/Encryption/Adapter/Mcrypt.php(171): rtrim()
Solution 1:-
I just installed it on my server using apt install php7.4-mcrypt
Restert apache server :-
service apache2 restart
Check php installed extention
php -m
Solution 2:-
Run below command
rm -rf var/cache/ generation/ chmod 777 -R var/ pub/ generated/
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