Hi Alberto, we had another report of the same thing this morning, with about:blank as the home page:

https://support.mozilla.org/questions/1183233 (unsolved)

In that case, clicking the Home button a second time completes the process.

I would be surprised if this was due to a change in Firefox. Maybe the two of you share an add-on in common??

The problem seems to be ADBlock Plus v3.0, as supposed in the other thread :( Also on another PC, same Firefox version but ADB v2.9.x works ok, when I have update ADB to v3.0 the problem appears. For me, also clicking 2-3-x times the HOME button don't clean the page. Then I disabled ADB and the HOME button comes back to work ok. Many thanks for the help ! Bye

Hello. Seems ADBlocker 4 has this issue as well. Also, in messing around with home button, I found that holding the shift key down and clicking the home button DOES clear screen first click every time for me when AdBlocker is enabled. Using home button WITHOUT shift key does NOT clear screen with AdBlocker enabled; happens every time I attempt this.

Also, disabling AdBlocker clears the fault for me as well every time.

Unable to determine the root cause; assume it to be AdBlocker at this point as it is reported that problem began when v. 3 of AdBlocker was released. However, there have been many releases of Firefox in parallel with that.