URL "about:newtab" still shows default and not custom new tab

But next problem, on browser start i get nothing, a blank page with title “New Tab” but with not any html code, that i can assume that my extension is not loaded. For me it makes such new tab extension useless and no idea howto answer such support questions.

I tried already everything, deleting profile folder, not logging in for Firefox sync etc. But i get always a blank page on start.

Please does anyone has an idea how i can handle it? Maybe just remove the following?

“chrome_settings_overrides”: {
“homepage”: “tab.html”
},

But no idea if this help when users do it by hand, maybe i have the same issue on start. I know only i cannot check with debugging extensions because its lost after restart and i do not want submit something to AMO just for testing. Another thing which i do not understand why developing is only “temporarily”… anyway.

Or what have to do that tab.html is shown on start?

Thanks a million again for help, Thomas