Ok, this is one of those really weird errors that seems like the machine’s just messing with you.
We have 2 websites, ASP.NET, both were 2.0, and we upgraded them both to 4.0.
They’re the same exact codebase, but the web.config files are different, they point at different databases, and they run as separate web apps in IIS.
After the upgrade, one works and one doesn’t.
The one that doesn’t work will throw a bunch of javascript errors around the Microsoft AJAX Control toolkit like ‘Sys is not defined’, ‘Type is not defined’, and ‘__nonMSDOMBrowser is not defined’ (in firebug). When I use the Scripts panel in firebug it lists all the different ‘…ScriptResource.axd?d=IOBqtxq…’ scripts, but when I ask to look at them, many of them will return ‘Failed to load source for: /ScriptResource.axd?d=IOBqtxq7p…’.
A couple of them do come back with the CodePlex copyright and some javascript, but many of them don’t. And the truly weird thing? If we recycle the app pool for the broken site, we don’t get those errors the first time we hit the site. The postback works, we log in, etc. Then we go back and hit it again, javascript errors are back and no postbacks.
Any ideas?
Ok, I hate answering my own questions, but since no one else is weighing in, this is the best we’ve come up with.
There’s a setting in IIS for the website that specifies Web Garden Threads, which I assume is how many threads to use if the site is in a load balanaced web garden. We had this new site set to 7, which is how it was in .NET 2.0. Apparently 2.0 is more forgiving (or ignores it), but 4.0 freaks out. The single request to the site is a request for lots of different resources, which end up being handled by different threads, which as you can imagine makes for chaos. And it’s different every time depending on which threads do what.
So, unless anyone else has an explanation for this, I’ll close this.