I tried running

pulumi state upgrade

after upgrading to Pulumi >=3.61.0, but I get

Upgraded 0 stack(s) to project mode

pulumi state upgrade
This will upgrade the current backend to the latest supported version.
Older versions of Pulumi will not be able to read the new format.
Are you sure you want to proceed?
Please confirm that this is what you'd like to do by typing `yes`: yes
Upgraded 0 stack(s) to project mode

Is that normal? I’m using S3 as my backend, and the project structure still looks the same (Pulumi.yaml is still present in the bucket, and there is no meta.yaml) This has been happening on all my projects, and there are several stacks in each project. Interestingly, I can still seemingly run pulumi commands as usual on newer versions.

What S3 folder are you logged into and what are the contents of that folder?

That was it, thank you @echoing-dinner-19531

👍 Nice when it's a simple fix