Blazor Server app on IIS fails when accessed with uppercase path (URL case-sensitivity problem)

[suryatejaKONDLA]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I am hosting a Blazor Server app in IIS under a subdirectory with <base href="/test/" />.
When I browse to domainname.com/test/ (exact lowercase with trailing slash), the app works fine.
But if I browse to domainname.com/test, domainname.com/TEST, or domainname.com/TeSt, the app fails with errors in the browser console:

Error: The circuit failed to initialize.
Error: Circuit host not initialized.
Error: Invocation canceled due to the underlying connection being closed.

Even though IIS still serves the request (and I can see a 301 redirect in DevTools when using rewrite rules), the same problem occurs: the Blazor _blazor SignalR circuit negotiation does not complete after the casing/format mismatch, and the app disconnects immediately. The error happens whether or not rewrite rules are applied.

Expected Behavior

If a user navigates to the app with different casing in the path (e.g., /TEST, /TesT, etc.), the Blazor Server app should still initialize and run normally. The SignalR _blazor circuit negotiation should not fail just because the virtual path casing does not exactly match the <base href>.

Steps To Reproduce

No response

Exceptions (if any)

No response

.NET Version

10.0.100-rc.1.25451.107

Anything else?

9.0.305
10.0.100-rc.1.25451.107
IIS 10
Windows Server 2019

[MihuBot]

I'm a bot. Here are possible related and/or duplicate issues (I may be wrong):

• Blazor has case sensitive URLs when hosted in a Child Directory #6818
• Blazor Base URI comparison is case sensitive #52288
• Blazor server IIS hosting url is case sensentive #23107
• Blazor Server behind reverse-proxy is case sensitive when app base path is changed #39469
• Blazor Server - the circuit failed to initialize #22494