In case it matters: Win 7 64 fully updated tb 31.1.0 lightning 3.3 (and about 18 other add-ons) --No other problems, with other mozilla products or any other product. Happy to post a quick video of what happens, if that helps, but it's just as described above. -D

using CCleaner? it deletes the sessions state files.

Not using CCleaner, but looked at the session.json file and sure enough, it seems to be created anew when I start tbird. I wonder what else could be affecting it? I've not installed any new software lately. Running MSE and Malwarebytes. On a whim, I added session.json to both security apps' exclusion settings. That didn't work. Any ideas?

I should also note that sessionCheckpoints.json is also created anew every time but sessionHistograms.dat.4little hasn't changed since 2012 and is likely deprecated.

happy to post the whole error console output (or any other logs.) The only interesting bits from today (and I use that term loosely):

Timestamp: 9/10/2014 10:15:16 AM Warning: mutating the Prototype of an object will cause your code to run very slowly; instead create the object with the correct initial Prototype value using Object.create Source File: resource://gre/components/steelApplication.js Line: 783

Timestamp: 9/10/2014 10:15:16 AM Warning: mutating the Prototype of an object will cause your code to run very slowly; instead create the object with the correct initial Prototype value using Object.create Source File: resource://gre/modules/Preferences.jsm Line: 378

Could not read chrome manifest 'file:///C:/Program%20Files%20(x86)/Mozilla%20Thunderbird/extensions/%7B972ce4c6-7e08-4474-a285-3208198ce6fd%7D/chrome.manifest'.

Could not read chrome manifest 'file:///C:/Program%20Files%20(x86)/Mozilla%20Thunderbird/chrome.manifest'.

now I'm seeing, that at least in tb 3.x, " Thunderbird 3.x deletes [session.json] after reading the settings. Its re-created and the layout saved when Thunderbird 3.x terminates normally."

...so the fact that the created date is always [last time I launched tb] might not be indicative of a problem. ...Which is not to say there's not a problem, just that what I thought was a red flag might not be. :(

Just updated to Thunderbird 32.0 which did not help the session problem.

Found another person with this problem after update to 31 https://support.mozilla.org/en-US/questions/1019328

Tried safe mode? (restart with add-ons disabled from the help menu.)

Could be a funky outcome from an add-on.

Just tried with daily and the tabs stay open. ( I use daily) But I await a compatible Lightning, like most days

Safe mode: No problem. Enabled just my fave 10 add-ons: Seems to work. Not sure why I didn't try this earlier. I've had to do as much multiple times in Firefox, but never in tb.

Matt, name a charity/cause. I'll donate $10 in your name. (e.g. Mozilla ;)

Thanks.

FYI: The offending plugin is likely one of these that I've now disabled: (Some of them were already disabled, but I don't recall which.)

Add-on Compatibility Reporter Allow HTML Temp Attachment Options CheckCompatibility ExternalTemplateLoader Folderpane Tools LookOut Provider for Google Calendar Remove Duplicate Messages (Alternate) Signature Switch TotalQuickFilter XNote++

Furthermore, I'd disabled addon compatibility check a-la http://www.groovypost.com/howto/disable-thunderbird-plugin-compatibility-checking/ ...which also might have affected things. Alas, I disabled that at the same time as everything else, so I can't be sure.

Might try to enable some other add-ons as needed. If I find the culprit, I'll report back.

I also had this issue and it was indeed fixed by disabling the modules. In my case the offending plugin was Folderpane Tools