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No. This is correct. Stacks have URNs, if you get the same stack twice, you'll have two URNs with the same value, which isn't allowed. You'll need to update your logic to not create StackReference objects for stacks that you already have StackReference ovbject for.

Thanks @little-cartoon-10569 . I did think it could possibly be getting the current stack but I had checked that and it wasn't. So I could only attribute it to not being able to reference the same stack in the next iteration where the previous had called it. So if I understand, when I

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or

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up

and as the stack is being evaluated to know what to do (create/delete resources), I can't call a new StackReference on the same stack. That's where the collision happens.

I don't follow. You've said that it's not the current stack, so what does "I can't call a new StackReference on the same stack. That's where the collision happens." mean?

Sorry, I see how my statement was confusing. Yes, it's referencing a stack in another project. I meant that the next iteration of a loop containing a call to the same StackReference (a stack in another project I need it's outputs) is what errors when

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because the internal state of this preview already had this stack reference called:

for (config of configs) {
 const stack = new pulumi.StackReference(stackInOtherProject);

 // exits here with Duplicate resource URN error

 const outputVal = await stack.requireOutputValue(‘myVal’);

 // some code here that is reached by config[0] but not config[1]
}

This is happening because stackInOtherProject has the same value twice? Is stackInOtherProject a value based on config? Or is it always the same value? If it's always the same value, you can move the stack reference constructor out of the loop.