Rated 5 out of 5 stars
I held off any updates of Firefox for a long time after reading the comments and not getting it to work with FF29.
InfoRSS is THE crucial addon for me and I wouldn't want to use Firefox without it. Tons of options, highly customizable with filters, you name it inforss has it. Although that comes at the price of intuitive usage it's definitely the best RSS/Atom reader for firefox.
However after today's upgrade to FF31 I managed to get it to work after a lot of trial&error. The key thing is that you have to right-click a toolbar, select customize, and then drag that blue globe icon with a dot to a toolbar. It has no text associated so you can only identify it by the icon. Once dragged it will do nothing. You have to make sure that the infoRSS option "Display->Position" is not set to Statusbar but top or bottom. Then restart Firefox and the infoRSS-bar should be visible and the blue globe icon gone.
After that I disabled the toolbar again to which I added that icon, but that's optional.
All the errors about podcast location and what not are also gone after that restart.
I'm using it with the Add-on "Classic Theme Restorer" in case that it matters. Now the only thing that's a bit of annoying is the transparent or dark background of the infoRSS bar on Windows7. Only the background of new entries can be set to a custom color.