You have not said what you tried.

Load the web page. Then, to reload the page bypassing the cache and force a fresh retrieval; Ctrl+Shift+R (Mac=Command+Shift+R)

Looks that you block some CSS files and that you have a transparent text color.

Do you see some text if you use CTRL+A on the web page to select all the text.

If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block (wanted) content (e.g. Adblock Plus, NoScript, Ghostery, uBlock Origin) always make sure such extensions do not block (wanted) content.

• make sure your extensions and filters are updated to the latest version
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

FredMcD said

You have not said what you tried. Load the web page. Then, to reload the page bypassing the cache and force a fresh retrieval; Ctrl+Shift+R (Mac=Command+Shift+R)

I tried all solution described in page: https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can, but not work.

Your solution did not work.

I see that the page specifies the Helvetica font.

• font-family: "Helvetica Neue",Helvetica,Arial,sans-serif;

We have seen in the past a lot of cases related to installed Helvetica fonts that aren't working properly.

You can check with the Font Inspector what font Firefox uses in your case and try to uninstall this font and other possible Helvetica fonts.

• https://developer.mozilla.org/en/Tools/Page_Inspector
• https://developer.mozilla.org/en/Tools/Page_Inspector/How_to/View_fonts
• devtools.fontinspector.enabled = true

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

cor-el said

Looks that you block some CSS files and that you have a transparent text color. Do you see some text if you use CTRL+A on the web page to select all the text. If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block (wanted) content (e.g. Adblock Plus, NoScript, Ghostery, uBlock Origin) always make sure such extensions do not block (wanted) content.

• make sure your extensions and filters are updated to the latest version
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

• My firefox is a new installation, I already tried to create a new profile, but nothing worked.
• I tried this solution https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems, but the problem persists.
• Problem is still in safe mode
• When I run via terminal, no error appears.

Thank you, but the problem still persists :(

My O.S: GNU/Linux Debian Testing (Debian 10, Debian Buster) Firefox version: 54.0.1 (64-bit).

cor-el said

I see that the page specifies the Helvetica font.

• font-family: "Helvetica Neue",Helvetica,Arial,sans-serif;

We have seen in the past a lot of cases related to installed Helvetica fonts that aren't working properly. You can check with the Font Inspector what font Firefox uses in your case and try to uninstall this font and other possible Helvetica fonts.

• https://developer.mozilla.org/en/Tools/Page_Inspector
• https://developer.mozilla.org/en/Tools/Page_Inspector/How_to/View_fonts
• devtools.fontinspector.enabled = true

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

Nice answer. The problem was precisely the broken helvetica font. I tried installing the fonts-freefont-ttf package, but it did not work, the font is broken directly into the package.

I downloaded an internet source package and removed the fonts-freefont-ttf package package from the system. With the package downloaded, I moved the font to /usr/share /fonts/truetype, reprocessed the font cache and everything worked again.

Thank you community