Teams Webinar ICS File Bug: Invalid 'PRID' property causes calendar import failures (RFC 5545 Violation)

Paul Gerhard 20 Reputation points
2026-07-23T03:20:28.96+00:00

Description: We are experiencing a critical validation error with the calendar invitation (.ics) files automatically generated for Microsoft Teams Webinars.

The platform-generated .ics files contain a syntax typo that violates the RFC 5545 iCalendar specification, causing calendar clients (such as Outlook and Apple Calendar) to reject or fail to parse the invitations automatically.

  • The Issue: The mandatory PRODID property is incorrectly rendered as PRID: in the VCALENDAR header block.
  • Expected Behavior: Per RFC 5545, the property block must explicitly use PRODID: (e.g., PRODID:-//Microsoft Corporation//Teams Webinar//EN).
  • Current Behavior: The raw file output generates PRID:-//Microsoft Corporation//Teams Webinar//EN, which is an unrecognized, invalid property.

Steps to Reproduce:

  1. Schedule a Teams Webinar with registration enabled.
    1. here is the example that triggered this issue: [Moderator note: Personally Identifiable Information removed]
    2. Download the generated .ics calendar file from the registration confirmation email or attendee portal.
    3. Open the .ics file in a text editor (e.g., Notepad) to observe the PRID: header string.
  2. Attempt to double-click import the file into a strict iCalendar-compliant client, resulting in an import error or failure to recognize the event metadata. (it does not work for instance in Gmail)

Requested Action: Please escalate this to the Microsoft Teams product group/engineering team to patch the string generation template so that it correctly outputs PRODID: instead of PRID:.

Microsoft Teams | Microsoft Teams for business | Calendar | Other
0 comments
Answer accepted by question author
Jade Ng 15,310 Reputation points Microsoft External Staff Moderator
2026-07-23T04:12:43.0266667+00:00

Dear @Paul Gerhard,

Thank you for reaching out and for providing detailed reproduction steps.

After reviewing the information provided, I can confirm that this appears to be a product-related issue rather than a tenant-specific configuration problem. The reported behavior indicates that the Teams Webinar-generated .ics file contains the calendar property PRID: instead of the RFC 5545-compliant PRODID: value, which may cause certain standards-compliant calendar clients, such as Gmail/Google Calendar, to reject or improperly process the invitation.

To ensure this issue is thoroughly investigated, it will need to be reviewed in detail by the Microsoft product team. As part of the investigation, the product team may analyze the generated .ics file structure and validate whether the webinar calendar generation service is producing non-compliant iCalendar content.

I sincerely recommend you try to create a support ticket from Microsoft 365 Admin Center > Support > New Service Request. You can raise support ticket from: https://admin.microsoft.com/Adminportal/Home?#/support/requests

The support team over there has higher permission than us to investigate the issue from background, they have more resource and correct escalation channel in handling this kind of issues. This would be a more efficient way in handling the case for you. 

For reference:  Get support | Microsoft Docs      

Thank you very much for your valuable time and your cooperation. Please feel free to reply below if you have any update or further concern!

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