711387 - "Default browser" modal dialog on start-up prevents Firefox from showing the "Restore Previous Session" button

Status: RESOLVED DUPLICATE of bug 654388

(Firefox :: Session Restore, defect)

Description

[Henrik Skupin [:whimboo][⌚️UTC+2]]

While I was working on security bug verifications I have had to switch between different versions of Firefox back and forth. Something which got my attention and I think is somewhat critical, is the fact that in Aurora the session sometimes is lost. No restore button will be visible in about:home, and even the menu entry for recently closed tabs is grayed out. Surprisingly the app tab I have created is still present.

For now I have seen this behavior when switching from release or beta to aurora. But never when switching to release or beta. So I think we should be safe for Firefox 9 but should investigate for Firefox 10 upwards. Further tests will have to be run to strengthen my current findings.

Steps:
1. Create a fresh profile with a release/beta version
2. Open a couple of tabs with different URLs
3. Make one of those tabs an app tab
4. Close Firefox
5. Open Aurora

With step 5 sometimes the session is lost and cannot be restored. Checking the error console I can see only one error which is related to session restore:

Error: formatURL: Couldn't find value for key: TIME_SESSION_RESTORED
Source File: resource:///components/nsURLFormatter.js
Line: 131

As Marco pointed out on IRC this constant is only used for mobile, so why do we make use of it on desktop?

http://mxr.mozilla.org/mozilla-central/search?string=TIME_SESSION_RESTORED

Comment 1

[Henrik Skupin [:whimboo][⌚️UTC+2]]

Ok, after some more tries I have nailed down this issue. It's directly related to the default browser check and the modal dialog we are presenting to the user. If the version of Firefox you are starting in step 5 is not set as default, you will always see this issue. It doesn't matter which version is used to create or prepare the profile.

The button can be made visible by just reloading about:home. The menu entry for restoring the last session is always available but clearly lacks visibility. 

Updated steps:
1. Ensure that the currently running version of Firefox is not the default browser
2. Open several tabs and restart Firefox
3. Press Cmd+R

After step 2 there is no "Restore Previous Session" button in about:home. Only with step 3 it can be made visible.

Not sure about the regression. It seems to exist already for a while. But I will check.

Comment 2

[Henrik Skupin [:whimboo][⌚️UTC+2]]

Turns out to be a dupe of bug 654388 which already has a patch reviewed.