Claude connector not able to update date fields

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I’m using Claude’s MCP connector to do daily updates and as of several days ago it lost the ability to update a date field (a date type custom field). I believe this first occurred about a week ago when Claude noticed the connector was updated. It gives me this specific error message and although it has tried multiple times with multiple other ways to update, other than one record at a time through the browser, it doesn’t seem to be able to solve this problem:

The update_tasks API tool does not support the date object format {"date": "YYYY-MM-DD"} required by this field — attempts returned "date_value: DayAndDateTime is not a JSON object".

If this is a bug in the connector, I’d love the ability to update custom date fields again via Claude through the connector. If there’s instructions, I can give Claude for another method (although it seems like it has tried everything), I’d appreciate those as well.

Thanks for any assistance

2

Hi @Sue_Cosby, welcome to the community!:smiley:

I have checked internally, and based on the review, this does not appear to be an Asana API bug, but rather an issue with how the Claude MCP connector is sending the date value.

In the Asana API, date custom fields must be sent as a JSON object, not as a plain text value. The correct formats are:

  • For a date-only field:
    {"date": "YYYY-MM-DD"}
    Example:
    {"date": "2026-04-13"}

  • For a date + time field:
    {"date_time": "YYYY-MM-DDTHH:mm:ss.sssZ"}
    Example:
    {"date_time": "2026-04-13T00:00:00.000Z"}

The error message you received:
“date_value: DayAndDateTime is not a JSON object” → typically occurs when the API receives a value that is not formatted as one of the required JSON objects above.

Suggested next steps

  1. Confirm the field type
    Make sure the custom field you are updating is a Date-type custom field in Asana.

  2. Verify how the connector sends the value
    Ensure the connector sends the date in the correct format, for example:

    custom_fields: {
  <date_field_gid>: { "date": "2026-04-13" }
}

    or (if using date + time):

    custom_fields: {
  <date_field_gid>: { "date_time": "2026-04-13T00:00:00.000Z" }
}

  3. If nested JSON is not supported

    If the Claude MCP connector only supports sending simple text values (strings) and cannot send nested JSON objects, this is likely a limitation of the connector itself. In that case, we recommend reporting this issue to the Claude MCP connector maintainers for further investigation.

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3

Let me also escalate this to further investigate. I’ll give you updates once I receive some. Thank you!

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4

Thank you. After following your instructions, Claude confirmed:

“That confirms the issue. The MCP connector’s schema enforces string or number only for custom field values — it can’t pass the nested JSON object {"date": "..."} that Asana requires. This is exactly the “connector limitation” Asana flagged in point #3.

The fix would need to come from the connector maintainers updating the schema to allow object values for date fields. Until then, the browser method in the skill remains the only working path for NK dates.”

It appears the connector is made by Asana. I’ll check with our point person on how to submit this to the connector team but if you have any guidance to help me getting this to the right people, I’d appreciate that.

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