Enable debugging in wp-config.php
// Enable WP_DEBUG mode
define( 'WP_DEBUG', true );
// Enable Debug logging to the /wp-content/debug.log file
define( 'WP_DEBUG_LOG', true );
// Enable display of errors and warnings
define( 'WP_DEBUG_DISPLAY', true );
@ini_set( 'display_errors', 1 );
And test to know if your error appear. You'll be able to fix it quickly.
2. Reset permalink
Don't know why but, sometimes, Wordpress have some weird error du to a old permalink.
I suggest you to
Going to Settings -> Permalinks
Switch permalink setting,
Save,
Replace it to your current configuration,
save it again.
- Deactivating all plugins.
if its works, activate plugin one by one to be able to detect which one create this error.
4. Refresh your .htaccess
place the basic wordpress .htaccess. Sometimes, some plugins change rules from your .htaccess and provoke many redirections error.
5. Switch your theme for a default theme without modification
It help you to know if a custom rules in your theme create this error.
6. Re-upload the wp-admin and wp-includes from fresh install
7. Reset folders write/read permissions
you can read Changing File permissions in Wordpress to help you to know what you should change and what it should do.