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!
Best Answer
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 optionsas 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.