There is a problem with Moodle’s ability to save uploaded files when we get the “Failed to write file to disk” error in Moodle. Bobcares, as a part of our Server Management Service offers solutions to every query that comes our way.

“Failed to Write File to Disk” Error in Moodle

An issue with Moodle’s ability to save uploaded files is indicated when we see the “Failed to write file to disk” warning. There are multiple causes for this, and all of them have to do with file system limitations or rights. Let’s look into some of the solutions for the error:

Modify File Permissions of the Site

When we talk about an issue with the site’s file permissions, we’re focusing on a specific folder called “uploads.” This folder is like a storage space for all the media files on the server. If this folder doesn’t have the correct permissions set, we’ll encounter an error message saying ‘Upload: Failed to Write File to Disk.’

To check if this is the problem, go to Tools > Site Health > Info page in WordPress. The uploads folder is usually located in the wp-content directory of the site. If we see that the uploads folder is present as ‘Not Writable’ under Filesystem Permissions, we need to fix its permissions. To do this, we’ll:

1. Use the SFTP client (like Cyberduck or FileZilla).

2. Look for the Info or Permissions section.

3. We’ll see a three-digit number with checkboxes. Change this number to 775. This number gives the server the necessary permissions to write files.

4. Save the changes and check if the error persists using the Site Health tool.

By adjusting the permissions for the uploads folder, we should resolve the ‘Upload: Failed to Write File to Disk’ error.

Clear WordPress Temporary Folder

We must have access to the files on the WordPress website, either using the file manager provided by the hosting company or by using an FTP/SFTP client, in order to clear the WordPress temporary folder. Follow these steps:

1. Use an FTP/SFTP program like FileZilla to log into the hosting account or create a connection with the server of the website.

2. Usually, the temporary folder can be found in the WordPress installation’s wp-content directory. Find it.

3. Locate the temporary folder, then open it and remove all of the contents, including files and folders. Usually, we may do this by selecting every file and folder, right-clicking, and selecting the delete option. As another option, we can pick the files and use the FTP/SFTP client’s delete button.

4. We may be asked to confirm the deletion by certain FTP/SFTP clients. Verify that we really need to permanently remove the files and directories.

5. Once the temporary folder has been cleared, return to the WordPress website and attempt the previous activity that was causing the ‘Upload: Failed to Write File to Disk’ problem. If the issue still persists, our Experts can help you fix it.

Verify Quota Limit for the Site and Server

The reason for the issue ‘Upload: Failed to Write File to Disk’ can be that there is not enough space left on the server. There is a limit on the amount of space we can utilize on the server, sometimes known as a quota limit. To verify the amount of space on the server:

1. Go to the hosting control panel.

2. Look for the usage statistics, which should be on the sidebar or in one of the screen’s corners.

If we see that we’re running low on space, it’s a clear sign that this is the issue. This problem is common, especially if we’re using shared hosting or a smaller plan from a managed WordPress host. There are two ways that we can solve it:
Either, we can increase the amount of space in the hosting package or move to a new hosting provider.

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Conclusion

The article offers three methods from our Experts in order to fix the “Failed to Write File to Disk” Error in Moodle.