You can try enabling
fopen on your hosting account, if it isn't enabled. This is usually done by adding a file called
php.ini in your Joomla site's root, then add the following line inside it:
allow_url_fopen = on
(some hosts have different methods to change php settings, e.g. GoDaddy requires the file to be called
fopen has been enabled by going to System >> System Information, then select the tab PHP Information and look for
allow_url_fopen, it should say
Other things to try:
- Go to System >> Clear cache, select all Cache Groups (if any) and hit "Delete"
- Go to Extensions >> Manage and select "Update" from the left hand side menu. Click "Clear Cache"
- Go to Components >> Joomla Update and click "Clear Cache"
If everything fails, you can try uploading the update package (or even the full installation package) to your hosting account. Unpack it to your Joomla root directory, overwriting any existing files.
Remember to always make a complete backup of your site before updating.