Known problems and solutions
Warning: mkdir(): No such file or directory in .../plugins/security-ninja/modules/vulnerabilities/class-wf-sn-vu.php on line 121 Warning: file_put_contents(.../uploads/security-ninja/outdated/outdated.dat): failed to open stream: No such file or directory in .../plugins/security-ninja/modules/vulnerabilities/class-wf-sn-vu.php on line 123
Sometimes you will find warnings in the debug.log file about a file, outdated.dat, that cannot be stored or opened on your server.
The error is related to the list of outdated plugins that is downloaded from the internet and then crosschecked on your website. If you have changed the permissions on the /wp-content/uploads/ folder it can cause problems or if you have added a limitation in the .htaccess that blocks requests to the uploads/ folder.
If you have any additional protection for your /uploads/ folder, please deactivate temporarily while you activate the plugin, this is when the plugin tries to download the file for the first time.