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Format_Invalid when importing csv file of attendees in zoom webinar


Hi all

I have hosted webinars using the zoom platform for a couple of years with no issues.
This week I hosted the first session of 2024 - I am on the Pro profile.
When I attempted to import attendee emails and names into zoom, I received an error message saying format_invalid, described as rows. I am using the template that zoom supply for importing attendees.
I have tried creating and saving the csv file in both numbers (Mac) and Excel with the same result.

I am using a Macbook Air. Not sure of zoom version but believe it is up to date.
If it makes a difference, I now live in France having recently moved from the UK.
I have sent 2 tickets into zoom support without an answer. The last one was TS0536661.
I tried sending myself a test confirmation email, and then used that content to send out an email to all the attendees.
Some attendees were able to access the live webinar as a result, and many were not - they were asked by zoom to register, and then received a message saying their registration was pending.
Any suggestions for a resolution would be warmly welcomed.


Community Champion | Customer
Community Champion | Customer



With Zoom Webinars registration, registrants can be imported by CSV upload and automatically approved. Once they have successfully been imported, a confirmation email will be sent to the registrants. 


Reasons you may have an issue;


  • The CSV file can only be up to 2MB.
  • Can only upload registrants to single-occurrence(non-recurring) webinars.
  • If charging a registration fee through Paypal is enabled for the webinar, this option will not be available.
  • If your registration has additional required questions, imported registrants will be redirected to the registration page to complete the missing required questions. 
  • Bad formatting 


Is your webinar a single occurrence or a recurring series ?



If my reply helped, don't forget to click the accept as solution button!


Hi Frank, and thanks for your reply.
Here are my answers to the points you noted:

  • The csv file is 4 kb
  • It is a single occurrence webinar
  • No registration fees have been charged through PayPal or any other platform
  • I didn't use the registration process on zoom - i used a separate platform for registration and then exported the data into a csv file that I then attempted to upload to zoom
  • I wondered about formatting - I have used the same process for the last 3 or 4 years without any previous issues. I also tried using the zoom template directly and that still came up with the same error message.
    I think it must be in this area, yet don't know exactly why it is happening?

Thank you, I do appreciate your thoughts.