If a company admin is getting an error trying to do a bulk upload of leads, here are several potential solutions:
Make sure to use the Chrome browser and clear cache and cookies.
There is a limit on the number of leads that can be imported at once. If importing more than 50 leads, break them into multiple files and upload those individually.
Ensure that the file format is CSV.
Ensure there is no missing information. ALL of the leads must have an email and phone number. If this information is not available for a lead, either remove them or add a placeholder email/phone number.