Knowledgebase
How to fix the problem with menus and tabs not working after upgrading SugarCRM
Very often after you upgrade your SugarCRM application you can't access the modules (e.g. Accounts, Home, etc.). When you click on the tabs in the navigation bar simply nothing happens. This doesn't mean that the upgrade is not successful. This issue is caused by incorrect permissions of the cache folder, or more precisely of its subfolders. To fix this problem you just have to set the correct permissions of the cache folder and all its subfolders. The permissions should be set to 755.
The cache folder is located in the root SugarCRM directory on your SugarCRM hosting account. If your SugarCRM is installed in a folder called sugarcrm in the public_html directory on your account, the path to the folder would be public_html/sugarcrm/cache. One way to change the permissions is with an FTP client (e.g. FileZilla). Don't forget to change the permissions recursively. This means to change the permissions not only of the cache folder itself but also of all its subfolders. For more information on permissions and how to change them read the tutorial on file permissions.
If when you change the permissions you're logged in your account in the SugarCRM application, after you change them log out. Then log in again and the tabs and menus in the navigation bar should work properly.