Toolbar buttons are missing in the administrator template.
There were CSS changes to the administration template and your browser is storing the out-dated version to speed up site loading. After performing an update it is ESSENTIAL to clear your web browser cache to reload the admin template CSS.
Refreshing the browser cache solves this immediately. If you do not refresh the browser's cache, you will not see the toolbar buttons until the new CSS file replaces the CSS file in the browser's cache(temporary internet files).
Here is how to clear a browser's cache by browser:
|*Note - some browser especially chrome can have very sticky browser cache and it is not enough to do a ctrl+f5. You might have to clear the browser cache by deleting temporary internet files. Refer to your browser's specific instructions to delete temporary internet files.|
If the problem persists you may want to check to see if your server has mod_pagespeed from Google enabled. If it does, and you want to keep using mod_pagespeed you'll need to flush the server side cache on upgrading to 3.1.x. You do this by logging into the server and then executing
A typical command and location:
sudo touch /var/cache/mod_pagespeed/cache.flush