Upgrading from IdentityServer 3 to 4 isn’t too tricky but there are some traps you can fall into if you are not careful.
Scopes are now API Resources
Scopes in IdentityServer 3 were used to define a resource and the secret required to get access to that resource. Now, this class has been updated to an API Resource as an example of how the new object might look like:
As you can see above the Scopes are now handled as a property of an API Resource. Clients now request an API Resource and a valid associated scope. If you forget to add the Scopes as I did you will get invalid Scope errors when trying to request a authorisation token so be careful to include them!
AddInMemoryScopes() Renamed to AddInMemoryApiResources()
Because Scopes are now ApiResources the method to add in-memory versions of them has been renamed – but can be used with the same type as before.
SetSigningCredential() Renamed to AddSigningCredential()
This is a minor change presumedly to make the intent of the method a little clearer and works the same way as before.
SetTemporarySigningCredential() Renamed to AddDeveloperSigningCredential()
Again as above this is just a naming change.
The above are the only changes I encountered when upgrading from version 3 to 4 and once I noticed the missing Scopes in the APIRescouce object the upgrade was pretty straightforward. There are probably other changes I didn’t encounter but hopefully, they are similarly easy to transition to!