1484399 - extensions.strictCompatibility reset when switch from Thunderbird 60.0 to 52.9.1 to 60.0

Status: RESOLVED INVALID

(Thunderbird :: Add-Ons: General, defect)

Description

[Eric Moore]

I have Thunderbird 52.9.1 and 60.0 installed in different directories, using the same profile. I'm using Windows 10 Home. I had set extensions.strictCompatibility false in version 60, checked that it was still false after exiting and re-starting Thunderbird 60, did some add-on testing using both versions and was surprised to find that somehow extensions.strictCompatibility was set true.

I found a repeatable sequence (at least on my PC) that causes this problem.

1. Set extensions.strictCompatibility false in version 60.0 using the config editor. Exit Thunderbird.
2. Run version 52.9.1. Verify that extensions.strictCompatibility is still false. Exit Thunderbird.
3. Run version 60.0 extensions.strictCompatibility is now set true and its status is default. 

The setting for extensions.strictCompatibility should have been unaffected by my running different versions of Thunderbird. It appears its value was reset.

Comment 1

[Jorg K (CEST = GMT+2)]

You need to understand how preferences work.

If you set the value to false in TB 60 and then run TB 52 where the value is false be default, this default is not stored.

Going back to TB 60 will give you its default of true. You lose.

If you want the value to stick, put it into user.js.

It's the same for every other preference.

Comment 2

[Eric Moore]

>It's the same for every other preference.

I knew about using user.js if you want to prevent prefs.js from changing a preference. I would expect when I switch to a different version that the value of any default settings might change. But this was a modified setting, and my experience has been that their value normally doesn't change when I switch versions. 

Did it change because that setting didn't exist before version 60? i.e. its special cased. I get the message that it's working as designed, but your explanation for why doesn't match what I'm used to seeing. You're essentially stating that if I change the setting for an account to compose a message from HTML (the default) to plain text that will automatically revert to the default setting if I use either a older version or a later version with the same profile. I've never seen or heard of that happening. It would be extremely annoying for ordinary users when they automatically upgraded if that happened.

Please take a moment and give me a more detailed description of when a setting might change due to switching to a different version. One of the reasons why I ask is I'd like to document that in http://kb.mozillazine.org/Testing_pre-release_versions

Comment 3

[Jorg K (CEST = GMT+2)]

Sorry, but there's nothing else I can add here.

If a preference is at its default value it will not be stored in prefs.js.

So if in version XX you change the pref from its XX-default value to the default value of version YY, then run version YY on the same profile, after exiting YY, the value stored in prefs.js is removed. Back in version XX you therefore get the XX-default value, although you changed it previously.

extensions.strictCompatibility has always existed and was always false. Now it's true.

We had the same issue with changing the default value of the HWA preferences.