Cannot Save Modules or Global Config
If you cannot save modules or global config anymore, you most likely have done some changes in the website that have caused this. To know the exact problem, you might need to revert the most recent changes in the administrator panel and check what is causing the issue.
As mentioned above, undoing the most recent changes might help to resolve this problem. If not, or you don not remember what was changed exactly, the first thing you should try is to upload a backup. This way you can fix the problem simply by restoring the website from a backup that was made when the website was working properly.
Another way you can try to fix the problem is by checking if the template you are currently using is not damaged. To do this, simply login to Joomla administrator panel and navigate to “Extensions -> Template Manager”.
In this page you will find the currently installed and default template.
To change to the default template, simply select another template and click “Make Default”.
If the problem with saving modules or global config is gone, this means the problem was related to the template you were using. But if the problem still exists, you will need to perform more steps to fix it.
Check if database is up to date. In Joomla administrator panel go to “Extensions -> Extension Manager -> Database”. Here you should see if the database is up to date. If yes, there is nothing you can do here anymore. But if not, you should see the following statement.
In this case, the database is not up to date and it needs to be fixed. To do this, simply click the “Fix” button as shown in the image below.
After clicking the “Fix” button and fixing the database, it should be fine.
You can also try cleaning the Joomla cache. This can be done in the “Extension Manager” by clicking on the “Update” tab.
Locate and click “Purge Cache” button to clean cache. After a successful cache clean you should get the following message “Purged updates”. Also, it is advised to turn off error displaying and magic_quotes_gpc. To disable PHP error reporting, simply go to System -> Glogal Configuration and click on the System tab.
Next, find “Debug Settings” and select “No” for “Debug System” as shown in the image below.
To disable magic_quotes_gpc you will need to make a modification to the .htaccess file by placing the following line “php_flag magic_quotes_gpc off” .htaccess file is located in the public_html directory of the Joomla installation.