Why is RefID tracking blank or Bad Request in Bookings?

How RefID is supposed to work#

Microsoft's booking page documentation says to add a campaign ID to the page URL, and gives this example:

https://outlook.office365.com/owa/calendar/TailspinToys@contosopetscom.onmicrosoft.com/bookings/?RefID=Twitter

The same page adds two warnings. Campaign IDs may only contain letters, numbers, underscores or hyphens, and "make sure you test your Campaign ID url". In February 2024 a Microsoft employee confirmed on Tech Community that the ID "will get attached to the appointment" and appears in the exported appointment data.

The export is the only place Bookings shows it. Go to the Shared Bookings home page, select Export, pick a date range and download the TSV file. The Tracking data field is one of the newer report columns.

What people report#

Other query strings have broken Bookings links too. See UTM parameters causing Bad Request.

How to test and troubleshoot#

1. Use a plain value. Start with something like ?RefID=test_01. No spaces, dots, % encoding, + or = in the value.
2. Make it the only parameter. Remove UTMs and any other query strings, then add them back one at a time once the plain version works.
3. Try both URL formats. Microsoft's example still uses the older outlook.office365.com/owa/calendar/.../bookings/ address, while current pages use outlook.office.com/book/.... Microsoft doesn't say whether RefID behaves the same on both.
4. Make a real test booking through the tagged link, not through the calendar view in the Bookings web app.
5. Export as an administrator. The FAQ says only staff with the Administrator role can download the report. Microsoft's docs describe the window as four-month periods in one place and "the past 120 days" in another, so choose a range that includes today.
6. Check a second source. If you have a Power Automate flow on When a appointment is Created, look at the TrackingData field in the run history. If it's filled there but blank in the export (or the other way round), you've narrowed down where the problem is.
7. If you get Bad Request, confirm the page opens without the parameter, then open a Microsoft support ticket with the exact URL. Community threads on this have been deflected, not fixed.

If RefID doesn't work for you#

Keep campaign data on your side. Tag inbound traffic to a landing page on your own site, record the source there, and link to Bookings with no parameters or only a short RefID code. The UTM parameters guide covers this, and GA4 conversion tracking explains how RefID fits into a server-side setup.

Doing this with BookingsXP#

BookingsXP doesn't depend on RefID. The widget captures UTMs, click IDs such as gclid and fbclid, the referrer and the landing page on your site, then writes them into the booking itself: into the booking notes, and optionally into a Bookings custom question you choose. Staff see the source on the appointment in Bookings and Outlook. See analytics and attribution. BookingsXP is independent and not affiliated with or endorsed by Microsoft.