BasicTestApp not resolving JavaScript files correctly

[maritogram]

I was trying to run the BasicTestApp for the Components' projects and I ran into the issue below:

I had run this project before, albeit about a year ago, and I don't recall having any problems with it? I managed to fix it for my case by removing the "subdir" inside of the index.html, but I'm left wondering why it's behaving like that? I cleaned, restored, and built everything as the docs suggested, therefore I'm a bit lost. Any input (or knowledge of it happening to anybody else) would be appreciated, thank you.

[AlexLimaTKZ]

Hi! I think you actually ran into a repo-side issue rather than a problem with your local restore/build.

There was a later fix that looks directly related to what you're seeing: #67903 — “Fix local WASM Components E2E 404 by applying gateway path base.”

The underlying problem was that the local WASM E2E fixture was passing:

--pathbase /subdir

but the Blazor Gateway binds the setting as:

Gateway:PathBase

so the gateway wasn't actually applying UsePathBase. The static asset routing therefore didn't line up with /subdir, which explains the 404s for things like:

/subdir/js/...
/subdir/_framework/...
/subdir/_content/...

The fix changed the fixture to use --Gateway:PathBase and also added the SPA fallback with:

app.MapFallbackToFile("index.html");

So your workaround of changing:

to / makes sense because it bypasses the broken path-base handling, but it doesn't appear to be the intended fix. The current BasicTestApp still has:

I would update to a current main and rebuild before keeping that local change.

Relevant fix: #67903 / commit 35b67fe

If it still reproduces on current main, it would probably be useful to mention whether you're launching BasicTestApp directly or through the Components E2E test infrastructure, since the fix specifically touched the WASM test fixture.