I've been using the Firefox Command Line Interface (Shift + F2) to take fullpage screenshots in Firefox for several months now.

Below is the syntax I use to capture screenshots via Firefox's CLI:

screenshot --fullpage filename.png

However, upon upgrade to Firefox 54.0, anytime I attempt to take a screenshot of a webpage it now returns with "unknownError" almost every time. On a few occasions, I've gotten the error "TypeError: this.target.tab is null" instead.

I've tried taking screenshots of dozens of different webpages both with and without the --fullpage parameter with no success. In fact, the only screenshots I've been able to capture are of Firefox's "New Tab" page and other Firefox pages, such as "about:config."

I'd greatly appreciate any help. Thanks in advance!

  • Same here. But even the about:config page screenshot is limited to the visible area. – DK Bose Jun 15 '17 at 4:23
  • On one laptop, I have Firefox 54 direct from Mozilla. On that, the screenshot doesn't work. On another laptop, which has the version supplied by the Ubuntu repos, it works fine. – DK Bose Jun 15 '17 at 11:09
  • I'm using the version supplied by Ubuntu. AFAIK the only difference is the Ubuntu Modifications extension, which I've had disabled for years. – PC_LOAD_LETTER Jun 15 '17 at 12:45
  • I also managed to find a bug report regarding this issue on bugzilla, indicating it was present in 53.0 as well. However, it worked fine for me in FF 53.0. bugzilla.mozilla.org/show_bug.cgi?id=1361110 – PC_LOAD_LETTER Jun 15 '17 at 12:48
  • I'm having the opposite problem: the CLI will still take a screenshot fine, if I can open the CLI in the first place. Most of the time I press Shift and F2 and nothing happens. Occasionally it deigns to open. – TRiG May 16 '18 at 14:17

It seems things may have changed... This is what I did:

First select Tools > Web Developer > Inspector.

Look for the little cog-wheel with Toolbox options as its tooltip. Click on the cog-wheel to open the Toolbox options.

Scroll down to Available Toolbox Buttons and look for "Take a screenshot of the entire page". Check its box. A little camera icon should now appear to the left of the Toolbox options cog-wheel. If you don't see it, close the Inspector window and reopen it.

Firefox full page screenshot

  • Nice find! I know they've been developing a more fully featured screenshot tool for some time, planned for a later release. – PC_LOAD_LETTER Jun 25 '17 at 19:30
  • 1
    I managed to find a way to enable the feature in about:config by changing "extensions.screenshots.system-disabled" to "false." A "Take A Screenshot" button will appear in the upper right hand corner of the browser. – PC_LOAD_LETTER Jun 25 '17 at 19:31
  • However, I like your solution better, as it's quicker and doesn't entail automatically uploading all screenshots to FF servers. Hopefully the CLI screenshot feature isn't being deprecated, as I like being able to set my own filenames. – PC_LOAD_LETTER Jun 25 '17 at 19:31
  • @PC_LOAD_LETTER : I do not see "extensions.screenshots.system-disabled" in about:config in my version of Firefox. I posted a separate question to address that at: askubuntu.com/questions/1065359/… – bgoodr Aug 14 '18 at 17:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.