Forum Discussion
Oct 12, 2025
Free/Busy Hybrid Exchange 2019
Hello everyone, I have a hybrid environment with Exchange Server 2019, with a dedicated Exchange application, we renewed the Exchange Auth certificate and then re-ran the HCW, however, free/busy is not working for 365 Pro local users. Has anyone had this problem? Could you help me?
3 Replies
- Sonai91Copper Contributor
You may validate accordingly, as per my below recommendations:
- Validate if the dedicated Exchange Hybrid Application has been updated with latest Self Signed OAuth certificate of Exchange server 2019.
- Validate if the the legacy Service Principal Key has been removed:
.\ConfigureExchangeHybridApplication.ps1 -ResetFirstPartyServicePrincipalKeyCredentials - Review all steps as per documentation: https://learn.microsoft.com/en-us/exchange/hybrid-deployment/deploy-dedicated-hybrid-app.
- Andreas HeinzlerCopper Contributor
we have the same problems, but can solve them with the script in this article.
Exchange Server Security Changes for Hybrid Deployments | Microsoft Community Hub Please review expire for federation certificate.