To view error messages, you can use the Browser Console (Ctrl+Shift+j or menu > Developer > Browser Console). I suggest using the Clear button at the top first, then switch back to the window with the page and reload it. After the error occurs, when you return to the console, you can click the CSS button at the top to hide style warnings so it is less cluttered. Of course, even with additional error information, I'm not sure forum volunteers can solve this one. After reviewing several results here -- https://www.google.com/search?q=operation+failed+requested+database+object+found+object+store+exist+opened -- it seems to be something that can occur intermittently depending on how the program/game you're running was written. It might also be an issue on the server side, as in this thread: http://forum.unity3d.com/threads/i-am-getting-this-error-an-error-occured-running-the-unity-content-on-this-page.372266/ ---- Regardless of where the problem lies in this case, we should have you confirm that database functions are not disabled on your Firefox. Could you check here: (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button promising to be careful. (2) In the search box above the list, type or paste '''index''' and pause while the list is filtered (3) Check the preferences starting with '''dom.indexedDB''' and make sure they are not bolded and "user set". If they are, right-click > Reset the preferences to restore the default setting. (4) In the search box above the list, replace index with '''stora''' and pause while the list is filtered (5) If the '''dom.storage.enabled''' preference is bolded and "user set" to false, double-click it to restore the default value of true.