"You do not have sufficient permissions to access this page error"
"Nemáte dostatečné oprávnění pro přístup na tuto stránku."

You may face this Wordpress error when trying to enter wp-admin admin area. I faced it on wp-admin page.

I tried moving all files from my other working wordpress site (remember to dont forget upload theme folder from your old site to see the site template, also backup all your old site files) It did not worked. So error had to be in database? It was not!

Here are some tips if you have issue with wordpress:

- try looking into .htaccess files
- try renaming wp-content/plugins folder and reload page to see if issue is caused by plugins
- try cleaning your borser history, cookies and restart browser or use other browser
- try renaming wp-content/themes/yourtheme to other name and default theme rename to yourtheme so you can see if issue is caused by theme
- try forcing mysql upgrade by going to phpmyadmin mysql manager and in table "wp_options" find db_version row. change the number, save and reload your wordpress site. it will do mysql update
- try enabling debuging in wp-config.php to see errors.
define('WP_DEBUG', true);
into the file.
- try backing up all site files and uploading clean wordpress installation. then copy mysql login details from old wp-config.php file to new one. If problem persist. Issue is with mysql probably or hosting filesystem (ask admin to check files permissions), or your computer you may try pointing your domain to other webhosting to see if its not your current webhosting issue.

Solution that worked for me:
Download mentioned file "force-upgrade.php" and run it from Your wordpress site root directory.