Reproducible on: Firefox 35.0b5 (20141218174327), Aurora 36.0a2 (2014-12-18), Nightly 37.0a1 (2014-12-18). Affected platform(s): Ubuntu 12.04 LTS 32-bit, Windows 8.1 32-bit and Mac OS X 10.9.5. STR: 1. Launch Firefox with a clean profile. 2. Access about:home in a new tab. 3. Type a random search term in the search field from the body of about:home and either press ENTER or leave the page as is. 4. Open a new tab. 5. Close the about:home tab and check the Browser Console. Expected result: The about:home is successfully closed with no errors thrown for this action. Actual result: Closing the about:home tab causes IDBDatabase.cpp:776 to throw the following error message: > IndexedDB UnknownErr: IDBDatabase.cpp:776 Notes: (a) The error message and its origin varies from branch to branch: (a.1) on Aurora 36.0a2 (2014-12-18): > An IndexedDB transaction that was not yet complete has been aborted due to page navigation. aboutHome.js:276:0 (a.2) on Nightly 37.0a1 (2014-12-18): > An IndexedDB transaction that was not yet complete has been aborted due to page navigation. aboutHome.js:278:0 (b) Firefox 33.1.1 (20141113143407) and Firefox 34.0.5 (20141126041045) are *not affected* by this issue. (c) On Nightly 37.0a1 (2014-12-18), the error is thrown with and without e10s enabled. (d) The error is *sometimes* thrown for searches performed from the toolbar as well, following the same steps.

I don't think there's a relation with the search, that error can happen if a transaction is running when we close the page, it is "expected" somehow (there's no way to handle that without slowing down the page unload) since you can close the tab at any time.