TFS 2018 answers a REST call with "Page not found."
Newer servers answer a too-new api-version with a JSON error that names the right version. Team Foundation Server 2018 does not. It sends its HTML error page with HTTP 404, so a tool that expects JSON shows "HTTP 404" or a parse error, and nothing says the version was the problem.
What comes back
HTTP 404 and an HTML page:
Page not found. - Microsoft Team Foundation Server Error The page you are looking for is currently unavailable. Page not found. Things you can try: Refresh the current page Go back to the previous page Sign in as a different user
Seen on a freshly installed TFS 2018 Update 3 (Express, October 16, 2026) for {collection}/_apis/projects?api-version=9.9, and for the projects and Git calls with api-version=7.1.
How to fix the call
- Send
api-version=4.1. On TFS 2018 Update 3 every pull request call we tried worked with it: listing, diff, comments, votes, completing. - Microsoft's table lists 4.0 for TFS 2018 (REST API versioning). We did not test a TFS 2018 before Update 3.
- If 4.1 still gives "Page not found", check the address: the collection is part of it, for example
http://tfs.example.local:8080/tfs/DefaultCollection/_apis/....
What TFS 2018 quietly ignores
Two requests get no error at all on TFS 2018 Update 3:
- Draft pull requests. A pull request created as a draft comes back as a normal one, open for review.
- Rebase and semi-linear merge. Completing with them makes a merge commit instead. Merge commit and squash work.
In IntelliJ IDEA, Rider and the other JetBrains IDEs
Azure DevOps Pull Requests is a pull request plugin for JetBrains IDEs 2024.1 or later. When it gets this page, it checks once with 4.1 and then talks 4.1 to TFS 2018 Update 2 and later; on an older server it says the server is too old instead of "HTTP 404". It turns the draft option off on TFS 2018 and offers merge commit and squash there. Reading is free; voting, commenting and completing are Pro, with a 30-day trial.
Get it on JetBrains Marketplace
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