Free Busy - From Cloud to on-premise not working

Brass Contributor

Hi everyone,


we have set up an Exchange hybrid configuration.

Everything works fine. Except the Free/Busy from Cloud to on-premise.


I read some (also opposite) blog posts and decided to follow this one:


We have executed the HCW therefore ended up with 



and the Other one ;)


I have checked the availbility of the autodisover from external with the MS connectivity test.

I tested the Oauth from Exchange online (Test-OAuthConnectivity -Service EWS -TargetUri etc)

I checked all URLs in the connectors


What else can i do or check? The TargetSharingEpr is empty. But according to the blog this is "normal". Other MS sites states this must be filled (for OrganizationRelationship). Other blogs set the IntraOrganizationConnector to "Enabled:false"


Can someone advise?


Thanks Stephan


1 Reply

Ok. The TargetSharingEpr was the one that was missing. ;)

Now the cloud user gets a "Security Popup" after trying to open an onprem calender. We are using Office 365 ProPlus.

Maybe an issue with modern auth? Is there a way to solve this?


Best regards