Start Firefox in Safe Mode {web link}

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

I am not understand. why run in safe mode? Firefox is working fine, it is occupying the disk. SSD 120 GB. Free 85 GB. After two days of continuous operation, free space is 0.

https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode

Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes), any userChrome.css/userContent.css files, and some other advanced features to help you assess whether these are causing the problem. If the problem goes away, that tells us one thing. If it does not, that tells us something else.

Will I still have open tabs?

What we want to find out is if the problem is still there.

launched, I will wait for the result. Usually the disk fills up in two days

How do you know Firefox is filling the disk? Is TRIM enabled for your SSD?

Killing the firefox.exe process frees up space. Trim included

Perhaps you need to reduce the about:config setting "browser.cache.disk.capacity". Edit: On second thoughts, that setting is unlikely to be as high as the usage you say is happening. I have mine set in megabytes, NOT gigabytes. You could look at other browser.cache settings also.

This usually happens at night when the computer is locked and not in use.

Is there a reason you leave the browser running? As a test, shut down Firefox when not in use.

I just don't turn off my computer. I'll try to close firefox at night

i come here for random solutions: install "everything" which is a file searching tool and search your ssd, see whats modified recently

I did so. Nothing is visible. Shows 40 GB used.

Try clearing the browser cache occasionally: [to clear the Firefox cache]

Safe Mode didn't help. The same place ran out every other day.

Many have reported issues using the 64bit Firefox. Install the 32bit version from; Download Firefox For All languages And Systems {web link}

Reinstalled to 32 bit. I will watch.

Now firefox crashes periodically. But it doesn't take up space.

In the address bar, type about:crashes<enter>. Note: If any reports do not have BP- in front of the numbers/letters, click it to submit them.

The crash report is several pages of data. We need the report numbers to see the whole report.

Using your mouse, mark the most recent 7 - 10 Submitted crash reports, and copy them. Now go to the reply box and paste them in.

Please, Do not post a screenshot ! !

For more help on crash reports, see; https://support.mozilla.org/en-US/kb/firefox-crashes-asking-support