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Value is not a valid date string

I’m trying to import some event-data within a google sheet via zapier into a collection of webflow. Works great exept for the field “date”. In Google the field is formatted as Date/Time:

1/1/2017 13:15:00

But zapier returns an error: returned (400) Bad Request and said "Field 'start-date-time': 
Value is not a valid date string: '1/1/2017 13:15:00'"

Any idea, how I have to modify the date-field in my google-sheet?


We use the date format defined by ISO 8601 ( It’s limited to just this format as accepting multiple date formats gets tricky since, as an example, there is no way to know if 2/1/2017 is Feb 1st or Jan 2nd.

So for your example date, the format would be: 2017-01-01T13:15:00.000Z


Hi @nathan

This format “2017-01-01T13:15:00.000Z” no longer works when sending a date through to the CMS “date field” custom field using Zapier. It returns the message "The app returned “ValidationError: Validation Failure”.

When I remove the date from the Zapier step then it sends through just fine. Could you help me understand why this isn’t working anymore?


I’m also having this issue when connecting Zapier to Webflow. I’m importing a date and time in the ISO 8601 format as explained above by the Webflow staff, but I’m having issues with the validation errors within Zapier. How do I go about utilizing the industry standard format within Webflow and Zapier?

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