I’m trying to use Zapier to send new Acuity Scheduling appointments (booked via Squarespace) to my GoHighLevel (GHL) calendar using a Webhooks by Zapier POST request to the GHL API. My workflow is as follows: Trigger: New appointment in Acuity Scheduling. Format: I use Formatter by Zapier to convert both the start and end times to ISO 8601 format with the correct timezone offset (e.g., 2025-05-09T10:30:00-05:00). The output from Formatter looks exactly like this, with the colon in the offset. Webhook: I send these values (along with other required fields) to https://rest.gohighlevel.com/v1/appointments/ with the proper API key in the Authorization header. Problem:No matter what I do, I keep getting this error “The end time must be a date and time with timezone offset. ex: 2020-10-25T10:00:00-11:00” I have confirmed there are no extra spaces or hidden characters. The startTime and endTime are different and both are in the correct format. I have tried hardcoding the value in the Webhook step and still get the error. I have removed optional fields like selectedTimezone to avoid conflicts. My Zapier account timezone is set to Central Time (America/Chicago). Example of my Webhook data:json"calendarId": "MY_GHL_CALENDAR_ID","title": "Cleaning Appointment","startTime": "2025-05-09T08:30:00-05:00","endTime": "2025-05-09T10:30:00-05:00","contact.firstName": "Test","contact.lastName": "User","contact.email": "test@example.com" What am I missing? Is there a Zapier-specific issue that could be causing this, or is there something else I should try?Thank you for your help!

Hi @Minty NowFor us to have more info, provide:screenshots showing how your Zap step is configured for the API requestthe link to the GHL API endpoint documentation you used to configure the API request

Webhook Fails: “The end time must be a date and time with timezone offset” (ISO8601 error)

I’m trying to use Zapier to send new Acuity Scheduling appointments (booked via Squarespace) to my GoHighLevel (GHL) calendar using a Webhooks by Zapier POST request to the GHL API. My workflow is as follows:

Trigger: New appointment in Acuity Scheduling.
Format: I use Formatter by Zapier to convert both the start and end times to ISO 8601 format with the correct timezone offset (e.g., 2025-05-09T10:30:00-05:00). The output from Formatter looks exactly like this, with the colon in the offset.
Webhook: I send these values (along with other required fields) to https://rest.gohighlevel.com/v1/appointments/ with the proper API key in the Authorization header.

Problem:
No matter what I do, I keep getting this error

“The end time must be a date and time with timezone offset. ex: 2020-10-25T10:00:00-11:00”

I have confirmed there are no extra spaces or hidden characters.
The startTime and endTime are different and both are in the correct format.
I have tried hardcoding the value in the Webhook step and still get the error.
I have removed optional fields like selectedTimezone to avoid conflicts.
My Zapier account timezone is set to Central Time (America/Chicago).

Example of my Webhook data:

json

"calendarId": "MY_GHL_CALENDAR_ID",

"title": "Cleaning Appointment",

"startTime": "2025-05-09T08:30:00-05:00",

"endTime": "2025-05-09T10:30:00-05:00",

"contact.firstName": "Test",

"contact.lastName": "User",

"contact.email": "test@example.com"

What am I missing? Is there a Zapier-specific issue that could be causing this, or is there something else I should try?

Thank you for your help!

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Hi @Minty Now

For us to have more info, provide:

screenshots showing how your Zap step is configured for the API request
the link to the GHL API endpoint documentation you used to configure the API request