Steps to reproduce the issue

• Set up a path with a space character in the $config->tmp_path variable (e.g. /Users/test/files/joomla projects/mysite/tmp)
• Start a joomla update in the joomla backend

Expected result

The joomla update process should run through as normal (update from 3.9.27 to 3.10.2).

Actual result

Update could not be installed. Got an error The checksum verification failed. Please make sure you are using the correct update server!.

Reason for this error

In file libraries/vendor/joomla/filter/src/InputFilter.php in method cleanPath (line 1017) a regexp for checking the path for Linux or Windows file systems fails. For Linux systems the patters is defined as:

$linuxPattern = '/^[A-Za-z0-9_\/-]+[A-Za-z0-9_\.-]*([\\\\\/]+[A-Za-z0-9_-]+[A-Za-z0-9_\.-]*)*$/';

This pattern does not accept any spaces. Thus a tmp_path containing any spaces will fail.

Solution

The pattern should allow space, e.g.

$linuxPattern = '/^[A-Za-z0-9 _\/-]+[A-Za-z0-9 _\.-]*([\\\\\/]+[A-Za-z0-9 _-]+[A-Za-z0-9 _\.-]*)*$/';

Then the method cleanPath will return the correct path and the update process works as expected.

Additional comments

Tested/reproduced on Joomla! 3.9.27 trying to update to 3.10.2