<t>If you are an Azure administrator getting this message, it may be for the the exact reason that is listed in the error message - you can not use the common API endpoint to MSFT logins to tenant-specific applications.<br/>
<br/>
In my case, I was configuring an app registration with sample code - the sample code needed to be modified with a new endpoint. I.e the following line:<br/>
<br/>
let kAuthority = "https://login.microsoftonline.com/common"<br/>
<br/>
needed to be changed to:<br/>
<br/>
let kAuthority = "https://login.microsoftonline.com/MY_TENANT_NAME"<br/>
<br/>
...or, if you have spaces/special chars in your tenant name, or would prefer a Key ID, use the Tenant ID:<br/>
<br/>
let kAuthority = "https://login.microsoftonline.com/MY_TENANT_GUID"<br/>
<br/>
The tenant name/ID for your Azure organization can be obtained by typing "Tenant Properties" into the Azure search bar.<br/>
<br/>
Xamarin: The above note worked for MSAL iOS - for Xamarin MSAL Android/iOS, there was no direct way to set the authority in the main call. It needs to be chained to the interactive login call.<br/>
<br/>
E.g., the sample code here:<br/>
<br/>
authResult = await App.PCA.AcquireTokenInteractive(App.Scopes)<br/>
.WithParentActivityOrWindow(App.ParentWindow)<br/>
.ExecuteAsync();<br/>
<br/>
```<br/>
<br/>
Needs to be changed to this:<br/>
<br/>
```<br/>
authResult = await App.PCA.AcquireTokenInteractive(App.Scopes)<br/>
.WithAuthority("https://login.microsoftonline.com/YOUR_TENANT_NAME")<br/>
.WithParentActivityOrWindow(App.ParentWindow)<br/>
.ExecuteAsync();<br/>
<br/>
```</t>
