In rare cases, even malware can cause this error, especially if it’s on the drive itself.

Most of the time, it is either related to poor system configuration, or an issue with your drive. There can be multiple different causes for this error. What causes the “Windows was unable to complete the format” error? “Windows was unable to complete the format” error solution.What causes the “Windows was unable to complete the format” error?.Use our guide to troubleshoot the formatting issue within no more than a few minutes. This can happen for several different reasons - however, it’s nothing you can’t fix. You might run into the “Windows was unable to complete the format” error. If you're trying to format a removable drive, such as an SD card or USB drive.