Go to '''about:config''' in the address bar and reset '''extensions.screenshots.disabled''' to '''false'''.

You can check these prefs on the <b>about:config</b> page (both should be false). *extensions.screenshots.disabled = false *screenshots.browser.component.enabled = false Taking screenshots can also be disabled via a policy (see about:policies). *https://support.mozilla.org/en-US/kb/see-active-policies-firefox-enterprise You can open the <b>about:config</b> page via the location/address bar. On the warning page, you can click "Accept the Risk and Continue" to open about:config. *https://support.mozilla.org/en-US/kb/about-config-editor-firefox