In the latest reviews, a lot of people are reporting this problem:

https://addons.mozilla.org/firefox/addon/theme-font-size-changer/

The author is very active and hopefully will fix it soon.

As a temporary workaround, you could try editing Firefox global scaling setting. This governs both the content area and the "chrome" area (menus, toolbars, and tabs).

(1) In a new tab, type or paste about:config in the address bar and press Return. Click the button promising to be careful.

(2) In the filter box, type or paste pix and pause while the list is filtered

(3) Double-click layout.css.devPixelsPerPx and change its value to 4.0, which is 4x the "traditional" size, and click OK. If that's not good, you can adjust smaller using 3.5 or upwards to 5.0, and so on.

Important: this is not a font size, it is a multiplier (4.0 = 400%), so if you get too small or too large, Firefox will become unusable. Please keep these values in a logical range.

This happened to me too, but another strange thing happened also. My chosen theme for FIrefox, a lovely purple elephant family was deleted and NOT by me. It happened at the same time.

Also a few other things went haywaire on my system so I ran Malwarebytes just to be certain nothing showed in the scan. It was clean.

I'm wondering just what was in the latest update of the Theme font and size changer. I managed to re-install it, still no icon for it, but my chosen font and size for Firefox was restored!

Hi goodwitch, do you want to check whether your theme is still on your system and whether it can be restored to being the default theme? You would do that on the Add-ons page. Either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Appearance. If you find the missing theme, click its Enable button.

If it's already enabled and doesn't appear, hmm, there's something wrong there. You might try reinstalling it from the Add-ons site if you can easily find it. https://addons.mozilla.org/firefox/themes/

hi goodwitch - the same thing happened to my theme and i had to search for it to reinstall it, as FF removed it completely. Safari is looking better and better....

Do you want to try rolling back to an earlier version of the extension? Here's how:

(1) Open the "Versions" page for the extension here:

https://addons.mozilla.org/firefox/addon/theme-font-size-changer/versions/

(2) Try the August 11th version (48.3) -- when you hover it, the green install button should appear

Some reviewers indicated they rolled back to 48.1 and that version is working for them... I don't know the difference between them.

(3) Go to the Add-ons page and set the extension to require permission to update. Either:

• Command+Shift+a (Windows: Ctrl+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Extensions. Then find the extension on the right side and click the tiny "More" link below its name.

Scroll down, and on the line for Automatic Updates, change from "Default" to "Off".

You can monitor the add-ons site and turn it back on when a fixed version appears.

Does that get you back up and running for now?

jscher2000, I had looked for the theme, it had been deleted so I went to find it and installed it again before coming to this thread.

This morning there is a new update for TF&SC 48.5 that fixes the problem. However mine did not update automatically so installed the new version from the link you supplied. Thanks a million.

I found a new bug in Firefox though, when I went to customize to pull the icon for TF&SC to the add-on bar at the bottom of the window I lost the theme from the top of Firefox, it still shows at the bottom. This happened yesterday too. Restarting Firefox fixes the problem, it is annoying though. Here's a screenshot to show what I mean.

Hi goodwitch, could you email the developer Baris Derin to see whether this is an issue with his extension? There's a contact link here:

http://barisderin.com/?p=39

HI jscher2000, sent him an email including the link to the theme and the screenshot posted above. I also noticed in the screenshot that the orange Firefox button, top left, had re-appeared. I use Classic Theme Restorer and had clicked to remove that a couple of years ago.

Firstly, why does'nt Firefox have a simple built in way of increasing the absurdly small font used in toolbars and tabs? (This should be possible without the need for an add-on!) Is Firefox unaware that a large portion of the planet does not have perfect eyesight ? Anyhow, I have been using Theme Font & Size Changer add-on which has worked well up until this morning when it suddenly stopped. I have tried installing the current version (yes the one updated as of today)but I keep getting an error message that prevents installation due to the add-on supposedly being corrupt. I then installed an earlier version that seemed to download ok, however no TF&SC icon appears anywhere, so I am unable to access the add-on. Please assist with a simple fix. Also, I messaged the author of this add-on but no reply. Thanks very much to anyone who can help.

charliez, when I installed the latest version because it did not update automatically there were 2 error messages that popped up. I clicked on OK on both of them and the update installed successfully. I used this link and just clicked on Add to Firefox

https://addons.mozilla.org/en-US/firefox/addon/theme-font-size-changer/

I've since scanned my system and nothing malicious was found. The update is not either infested with malware or corrupt. The icon was to the left of the location bar instead of to the right when I looked for it.