What is your goal?
I want to automatically schedule Instagram posts from Google Sheets to Metricool. The system should take rows with status “new”, calculate the next Wednesday or Saturday, create a draft in Metricool, and save the calculated date back into Google Sheets.
What is the problem & what have you tried?
I always get the error “Invalid date in parameter ‘publicationDate’”. I tried formatting the date using formatDate with ISO format, using parseDate from Google Sheets, and generating the date dynamically with addDays logic, but Metricool keeps rejecting the date.
Error messages or input/output bundles
BundleValidationError
Invalid date in parameter ‘publicationDate’
Hi @Andreas_Praxmarer
Metricool’s API is very strict about the date format it accepts for publicationDate. It typically expects the date in ISO 8601 format with timezone offset included, like 2025-04-09T10:00:00+00:00 not just a plain date or a date without the timezone. In your Make scenario, when formatting the date use formatDate with the format YYYY-MM-DDTHH:mm:ssZ and make sure a specific time is included, as Metricool won’t accept a date-only value without a time component.
Spent way more time on that “Invalid date” error than I’d like to admit, because everything looked correct until you realize Metricool just rejects anything without a full timestamp and timezone. Once I forced the format properly, it finally went through. Phonexa actually handles date formatting a bit more predictably, so switching back to this setup made the issue stand out right away.