Booking Error Message

Because the appointment is actually created, ask users not to submit the form a second time when they see the error; repeated attempts can create duplicate bookings. First confirm the business time zone, each staff mailbox time zone, and the service schedule all use the same supported Windows time-zone entry.

The Alberta time-zone change is a useful lead. Create a duplicate test service with no staff rotation, no Teams meeting, and email notifications disabled. Use a time zone already recognized by both Bookings and Exchange that has the same current UTC offset, then submit one booking. If the success page appears, re-enable notifications and meeting creation one at a time. Keep the temporary choice documented and review it when daylight-saving rules change.

If the error still occurs after the time zones are aligned, preserve the created appointment and give Microsoft support its booking ID, service name, staff mailbox, business time zone, customer time zone, and UTC submission time. That lets them trace the response failure without guessing from the browser message.

I ran into this issue I am based in alberta, Alberta switches to permanent UTC-6 time on November 1, 2026. Microsoft added a new "Alberta" time zone for that, but its booking server doesn't recognise it yet. When I set up the page, I picked "Edmonton, Alberta", which selected that new zone. From then on, every booking showed this exact same issues you described

I changed it to (UTC-06:00) Saskatchewan to make it work. 

The public page says the appointment failed, yet the event is created in Bookings and Outlook, even in different browsers. Availability probably succeeded and the failure occurs after creation, during the response, confirmation, or notification stage. Avoid repeated production tests because each may create another appointment. Check Microsoft 365 Admin Center > Health > Service health for a Bookings or Exchange advisory. Then create one test service with email, SMS, Teams meeting, custom fields, and follow-up notifications disabled, and book from the direct Microsoft-hosted page rather than an embedded page. If that succeeds, re-enable options one at a time to isolate the failing step. If the error remains, record the UTC time, booking calendar, service, staff member, customer address, and resulting appointment ID. Keep the created bookings and open a Microsoft 365 support request with those details; this inconsistent server response cannot be repaired reliably from the browser