If you’re experiencing an “infinite redirect loop” when trying to access the /wp-admin section of your WordPress site, it is most likely because the files on your server were updated and the permissions weren’t set appropriately.
By setting the permissions to 644 on all of the php files, this solved the problem for me.
If your server is on a unix system, you can use the following command which will look for all php files in the current directory and chmod them to 644.
find *.php -type f -print0 | xargs -0 chmod 644
I had to set the permissions on the wp-login.php file, as well as all of the php files in the wp-admin directory in order for everything to work properly.
chmod 644 wp-login.php cd wp-admin find *.php -type f -print0 | xargs -0 chmod 644
Good luck!