My homepage, search engine, is now /notfound.
I have been using Startpage as my search engine forever. Startpage has a new option to delete cookies when you x out of a tab. It has a different url than the regular Startpage. I tried to get Firefox to accept it. Two thousand variations, iterations later, and I still couldn't. Now when I open Firefox it says, startpage.com/ not found in a big red ribbon at the top of the page. Firefox won't let me go back to the old one either. There are other things but I'll start with this.
Alla svar (3)
If you manually navigate to Startpage using the address bar, does that work, or does it give you a similar error?
If the address bar method works and you have the "Home" button on your toolbar, you can drag and drop the lock icon from the left end of the address bar onto the Home button to update your home page address to the working one. See: How to set the home page.
If the problem is that you used a hidden feature to create your own search engine, try changing your default search engine to Google/Bing/DuckDuckGo for the time being until we can get that sorted out. See: Change your default search settings in Firefox.
You can check for issues with Total Cookie Protection.
My Startpage search engine is working as expected. Try installing one from the Mycroft Project.