You may receive this error when trying to upload the csv file for your Bulk Upload User Photo job.
File contains invalid (non numeric) userids.
This error displays when there is a character entered into the userid field that is not a number. If there are no letters or symbols in the userid field, it could be due to a space added at the beginning or end of one of the User IDs within the csv. When the space or character is removed from the userid field, the file will process.