Unable to upload file to WordPress website hosted on Plesk: Missing temporary directory

Vladimir Levchuk

Updated October 10, 2024 10:58

kb: technical Plesk Obsidian for Linux

Applicable to:

Plesk for Linux

Symptoms

Unable to upload a file in Wordpress > example.com > Log in > Media > Add New with the following error

Missing temporary directory

OR

Missing a temporary folder
There are the following records in /var/www/vhosts/system/example.com/logs/error_log file:

AH01071: Got error 'PHP message: PHP Warning: File upload error - unable to create a temporary file in Unknown on line 0\\n', referer: https://example.com/wp-admin/upload.php

Corresponding PHP-FPM service has PrivateTmp enabled:

# systemctl cat plesk-php83-fpm.service | grep PrivateTmp
PrivateTmp=true

Note: the PHP version can be identified in Domains > example.com > PHP Settings.
PrivateTmp=true means that uploaded files use directory like below:
/tmp/systemd-private-a843c1c414a649b6a153d621c2607c9e-plesk-php83-fpm.service-UuymOU/tmp/

Cause

PHP /tmp folder has been removed recently with rm -rf /tmp/* command. The temporary folder might also be removed by 3rd party tools, like tmpreaper package.

Removal of PHP temporary folder resulted in inability to upload files on websites that use certain PHP-FPM handler.

Resolution

Warning: If there is a 3rd party tool software deleting the temporary files, such as tmpreaper package, make sure to configure it properly or uninstall it from the system to avoid any conflict with Plesk and other services

Log into Plesk
Identify the PHP version used by the domain in Domains > example.com > PHP Settings:
Restart the corresponding PHP service in Tools & Settings > Services Management by clicking the restart icon. This will recreate the temporary folder:

If the error still triggers after restarting PHP service, do the following:

Navigate to Domains > example.com > PHP Settings
Change PHP parameter open_basedir to none and press Apply button.
Revert the changes, and press Apply button again.