I honestly don't understand the physics behind this problem, but for about an hour today I was getting a javascript error on a webform whenever it would postback:
WebForm_PostBackOptions is undefined
Browsing the 'net for a while I found out that the WebForm_PostBackOptions method is included in the WebForms.js javascript file (this file is referenced by ASP.Net pages to power their clientside functionality). I was doing an ASP.Net 2.0 project, but for some reason the browser was holding onto a WebForms.js file referenced from a 1.x project - and so, probably, this method only exists in the most recent version of the .js file and not the older one (which explains why the method is 'undefined'). When the browser tried to execute code, then, it blew up.
The fix? I simply cleared the browser's local file cache by going Tools > Internet Options > Delete Files... (and deleted all offline content). I then went back to the page and everything worked fine. Now that I got everything working I don't have the luxury of going back and understanding exactly how it happened, but it sure was frustrating...
...if this method works for someone, or if they found a better way to fix it, or know how it all started, feel free to fill me in....
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