Can't login after update – login page just refreshes with no error message

Try:
– switching to the default theme by renaming your current theme’s folder inside wp-content/themes and adding “-old” to the end of the folder name using FTP or whatever file management application your host provides.

– resetting the plugins folder by FTP or phpMyAdmin.

– re-uploading all files & folders – except the wp-content folder – from a fresh download of WordPress. Make sure that you delete the old copies of files & folder before uploading the new ones.

– running the upgrade manually via wp-admin/upgrade.php

I renamed all themes except the twentyXXXX themes, renamed the plugins folder, re-uploaded wordpress (exept wp-content) and wp=admin/upgrade tells me my current install is up to date.

Since following those steps, the main website now shows up only as a white blank page. It was working before, i just could not log in…

Try checking your site’s error logs for a more specific error message. Your hosts should be able to help you in accessing your site’s error logs.

from 1and1 help FAQ:

Since we don’t provide access to Apache error logs on shared hosting packages for technical reasons, you can create your own error logs for debugging PHP Scripts.

Any idea how I go about doing that?

You can try turning debug on and enabling error logging but, if the error is very early in the load process, this may not be sufficient.

WordPress database error: [INSERT command denied to user ‘dbo260219356’@’74.208.16.37’ for table ‘main_options’]
INSERT INTO main_options (option_name, option_value, autoload) VALUES (‘auth_key’, ‘M>h@KnF7ALGq7Ly_&Xufz*R6j/364 9bTC!|SY=8NUTcuAWFsO2bpzi_,{ZuESt', 'yes') ON DUPLICATE KEY UPDATEoption_name= VALUES(option_name),option_value= VALUES(option_value),autoload= VALUES(autoload`)

WordPress database error: [INSERT command denied to user ‘dbo260219356’@’74.208.16.37’ for table ‘main_options’]
INSERT INTO main_options (option_name, option_value, autoload) VALUES (‘logged_in_key’, ‘ubbvE(3:+ m[WL3U4^vk9y_WPy4DYDM,SB$}m]^a:ba!iOyt0r#(Ir+HC5Sh%A’, ‘yes’) ON DUPLICATE KEY UPDATE option_name = VALUES(option_name), option_value = VALUES(option_value), autoload = VALUES(autoload)

Warning: Cannot modify header information – headers already sent by (output started at /homepages/28/d91226652/htdocs/ltmb/wordpress/wp-includes/wp-db.php:1056) in /homepages/28/d91226652/htdocs/ltmb/wordpress/wp-includes/pluggable.php on line 680

Warning: Cannot modify header information – headers already sent by (output started at /homepages/28/d91226652/htdocs/ltmb/wordpress/wp-includes/wp-db.php:1056) in /homepages/28/d91226652/htdocs/ltmb/wordpress/wp-includes/pluggable.php on line 681

Warning: Cannot modify header information – headers already sent by (output started at /homepages/28/d91226652/htdocs/ltmb/wordpress/wp-includes/wp-db.php:1056) in /homepages/28/d91226652/htdocs/ltmb/wordpress/wp-includes/pluggable.php on line 682

Warning: Cannot modify header information – headers already sent by (output started at /homepages/28/d91226652/htdocs/ltmb/wordpress/wp-includes/wp-db.php:1056) in /homepages/28/d91226652/htdocs/ltmb/wordpress/wp-includes/pluggable.php on line 876

Did you backup your database before you tried to upgrade?

I run daily backups and have a sql.gz file….

I suggest that you try restoring one of your backups and running the upgrade again. I think your database has been damaged.

any advice regarding how I do that….I have the file just no idea how to make it work…

Thanks for all your help!

Have a look at Restoring_Your_Database_From_Backup.

It returns this error: #1142 – INSERT command denied to user ‘DBNAME’@’SERVER_IP’ for table ‘main_comments’

When I run show grants it says: #1044 – Access denied for user ‘USERNAME’@’%’ to database ‘mysql’