How to recreate an Agent Pool with the old name in AzureDevOps? - azure-devops

Question

I have troubles creating a new agent pool in AzureDevOps.
What I wanted to do was to remove an old Self-Hosted host and deploy a new one. However, the Agent-Pool used by the old host and to be used by the new one was created by a co-worker. This let to the case that I was unable to remove the existing registered agents causing conflicts during deployment of the new host. To resolve this issue I was able to remove the agent pool.
Now, when I want to create a new pool with the same name, I get the error message
"No agent pool found with identifier 76".
Did anybody ever see this error message and or has an idea what I can do about it?
Expected:
A new agent pool with the same name as the old pool is created.
Actual:
I receive the error message "No agent pool found with identifier 76".
Agent creation Image
Error Message Image

Answer 1

So apparently if you delete the Agent-Pool via the Project-settings menu, they are still available under the Organization-Settings menu. 
If this pool belonged to somebody else, you seem to loose even a reader role on this group there. In other words, it appears as the group is deleted even though it really isn't. 
It's very unfortunate the error message does not actually tell you these exactly.
The solution for us was that the Organization-Admins made us as Administrators of the group again. Following I was able to clean it up under Organization-Settings and use it again.​

Answer 2

As discuss some details with A.S. and test on my side, I have figure it now.
The root cause of this error is that your account is not a Administrator role. You can check this message from this doc.
If you are one of PCA, even though you are Reader of this agent pool or not any role, you can still add agent pool. And the other solution I found is that you need be added as the Administrator of this agent pool instead of be as one of PCA. You must meet one of the above two solutions, can add it without any error.
In addition, for error message displayed in pages and in F12 console.
As you can see from the pic I mentioned, this caused the error message which showed in pages. I know, the error message of console is easy to misunderstanding. It let you confusing why it response 404 not found.
This still relevant with Administrator role.
https://dev.azure.com/{org name}/3307xxxxxxx5676e/_apis/distributedtask/queues?authorizePipelines=true
This api which showed in console is used to search agent pool under Org setting.
While you are not administrator of org/agent pool, it could not find out the agent pool you want to operate, because you don't have permission to search it under Org setting. And then, it says "sorry, 404 not found", even though it exist under org setting. This is not a bug, just for logic.
So, agree with you, the error message it not too clear to understand the root cause.
In addition, if you just delete the agent pool under project setting, it still exist under org setting. Just need administrator role, you can add it back again without any error.