I have a document approval workflow where I added 2 users. One of the users was added using a wrong account. I was not allowed to edit the task and redirect to the correct account, so the only option was to delete the user with the wrong account and add the user with the correct account. The user was then able to approve the document. The 2nd user also approved the document. However, the overall status of the document shows it is "Rejected" instead of "Approved". The event history shows that right after the user was deleted, the task was auto-cancelled. After the task was auto-cancelled, the workflow was Rejected. Why? Can the current document status be corrected? Can this be prevented?
Since, you changed the configuration of the workflow(list of approvers) at the time when some(at least one, which you are talking about) of the workflows were in progress. SharePoint
auto-cancelled these workflows to prevent any data inconsistency due to change in the configuration.
If you have the option enabled and have the permissions, you can manually re-initiate the canceled workflows.