I am using Sitecore search in the content tree, but the search bar is not working. When I click on the search icon in the content editor to open the search tab I get the following JavaScript error on the console.
Uncaught TypeError: Cannot read property 'd' of undefined
Since this a JavaScript error, I tried to open the search from FireFox and IE but I got the same issue.
Also I installed a clean instance from Sitecore, but I still see the same error.
Check if you got any url rewrite forcing lowercase or uppercase as the itembucket.asmx that is called is Case Sensitive. This was the culprit for me. Hope that helps.