Test-OAUthconnectivity against O365 fails

[Frankie380]

Hi I have run HCW on my on premise exchange server for full hybrid classic type and the communication between exchange online and on premise seems not to be running smoothly.

Here is the result of the Test-OAUthconnectivity result. It seems to fail when building the token.

Test-OAuthConnectivity -Service EWS -TargetUri https://partner.outlook.cn/ews/exchange.asmx -Mailbox <on premise mailbox>-Verbose | fl

Error:[OAuthTokenBuilder:GetAppToken] unable to continue building token; no locally configured issuer

              was in the trusted_issuer list, realm from challenge was also empty. trust_issuers was

              00000001-0002-0000-c000-000000000000@*

              Error:The trusted issuers contained the following entries '00000001-0002-0000-c000-000000000000@*'. None

              of them are configured locally.

[#2]

@Frankie380 So I had the same issue yesterday and here is how I solved it.

So the error has something to do with Accounts access control endpoint. The HCW adds this as an Authentication Server in Exchange OnPrem. 

I checked the settings on it and one thing looked off to me. under the domain names, I found my main DomainName added as autod:contoso.com. Everytime I've set up HCW or OAuth manually, I always added the domain without autod:contoso.com. 

So I removed the domain using set-AuthServer -identity "ACS*" -DomainName @{Remove="contoso.com"}

the added it back again with: set-AuthServer -identity "ACS*" -DomainName @{add="contoso.com"}

This caused the autod: prefix to be removed. Did an IISReset, after that Free/Busy started working.

Good luck