You need to go to the extension manager and enable Addons to run in private mode.

The option to enable extensions by default in Private Browsing mode has been removed quite some time, because it causes issues with extension that weren't allowed to run in PB mode via their manifest like extensions the use containers. You will have to move the slider for each extension in the extensions manager.

• https://support.mozilla.org/en-US/kb/extensions-private-browsing

The option to enable extensions by default in Private Browsing mode has been removed quite some time, because it causes issues with extension that weren't allowed to run in PB mode via their manifest like extensions the use containers. You will have to move the slider for each extension in the extensions manager.

• https://support.mozilla.org/en-US/kb/extensions-private-browsing

Is there a bug about it at https://bugzilla.mozilla.org/describecomponents.cgi?product=Firefox? I ask because it appears that you are aware of a time when this functionality was available. Even if closed, I'd like to follow the issue in case it's reconsidered.

This won't be reconsidered.

• 1661517 - Remove extensions.allowPrivateBrowsingByDefault preference [91]
• 1627939 - Problem with extensions with incognito: not_allowed in their manifest and flag allowPrivateBrowsingByDefault

• https://bugzilla.mozilla.org/page.cgi?id=etiquette.html