507109 - Need more reporting/info in cross-domain request scenarios

Status: UNCONFIRMED

(Firefox :: General, enhancement)

Description

[Richard Fine]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.1.1) Gecko/20090715 Firefox/3.5.1 (.NET CLR 4.0.20506)
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.1.1) Gecko/20090715 Firefox/3.5.1 (.NET CLR 4.0.20506)

When issuing an XHR cross-domain, there's basically no information on HTTP Access Control mechanism failures - if a preflight fails, or the actual request is blocked/discarded (e.g. because useCredentials=true but there's no Access-Control-Allow-Credentials: true header), there's no exceptions (at least, not that get reported in Firebug) or console messages. This makes it really hard to debug...

Reproducible: Always

Steps to Reproduce:
1. Issue an XHR cross-domain to a server that isn't Access-Control aware or in such a way as to not comply with its Access-Control policies.
2. Check the error console.
Actual Results:  
No warnings/messages.

Expected Results:  
Some kind of warning message at least indicating that the XHR /was/ blocked for access-control reasons; even better would be something that indicates exactly /why/ it was blocked (i.e. that indicates which step of the checking algorithm it failed at).

Comment 1

[benson margulies]

I'm getting informative exceptions in FF8.