Unable to create AWS CodeBuild Webhook

I think it was a server error on AWS' side. I tried again 4 hours later and it's suddenly working now.

For other people coming here looking for a solution: For us, it was about the 20 webhook limit per a GitHub repo. We have a monorepo and currently have a trigger for each projects pipeline, which obviously doesn't work out anymore. Obviously a more helpful error message would've saved several hours of debugging...

I ran into the same problem and was able to resolve it by getting proper permissions for my Github user. Basically my Github user did not have access to create a webhook, though I had permission to read the repo.