Yesterday I had a fully operational stack. Then today I tried to re-import an Azure resource group with

pulumi import

that was protected. Now when I do

pulumi up

it gives an error saying that the stack itself is a duplicate, and I can't get it back to a working state.

pulumi:pulumi:Stack (PulumiArm-hco):
    error: Duplicate resource URN 'urn:pulumi:hco::PulumiArm::pulumi:pulumi:Stack::PulumiArm-hco'; try giving it a unique name

you made no code changes to your pulumi program at all?

Actually I did add new AzureAD app registrations... and now that you mentioned it, I see that removing the additions causes the error to go away.

Usually I see this error when calling one of the delegate overloads to initiate your pulumi program, and also instantiating your own

Pulumi.Stack

in your program. There can only be 1

Pulumi.Stack

instance in any given pulumi program and the delegate overloads for running a pulumi program (instead of providing a TStackType) usually instantiate a stack for you so you can inadvertently end up with 2 being instantiated But if you're just adding app registrations than I'm not sure, may need more information

Ok I see the problem now. I was trying to run my new app registrations separately instead of merging the new registrations together.