I'm sorry to hear that. Just so you know. Tab history can be deleted if the addon is removed. Yes there were some reported cases where it went blank even without that, but in the case of Bookmarks. If any bookmarks was removed after firefox crashed, that can be the addon fault. The addon will never under any circumstance delete Bookmarks randomly. It will only delete if you specifically delete something yourself but other than that, what is saved as bookmarks (the Session tab) remains saved and will never be deleted by the addon even if you remove the addon. Bookmarks are there and it was the only way to make sure that data will be preserved no matter what happened to the addon or if you removed it. I can assure you that if you lost any bookmarks Firefox the addon is not the one to blame here. Make sure you backup your bookmarks once is a while, or use a Firefox account to sync then across many devices. Usually Firefox keeps multiple bookmarks restore points, just make sure you check all of them because I really don't know why would the bookmark vanish just like that. If you need more details please contact me over email (use the Feedback button from the addon)

I don't really know what to say. It's true that the addon doesn't do that. But, at the same time it was never really meant to do that. Receiving a negative feedback because the addon doesn't do something I never intended to seems a little bit weird, even if you may consider these features as really important and critical for such an addon. Please have in mind that each particular addon is implemented with a certain set o features, and many new features can be added later or will never be added because they are not in line with the addon vision. That's why there are multiple options out there, because there are many developers that though of implementing similar useful things. Not having something in an addon, doesn't mean it's bad, it may simply not be for you. Thanks for review anyway.

Hi. Thanks for review. I will assume that you are talking about manually saved session and not the one from the auto-save tab. The only reason any blank space might appear after you delete a session is if you ordered them by something else than position.
But then... you say that everything is blank ?! But that can't happen for manually saved session because the addon never ever touch that data automatically so deleting it is out of the question.
Please if you can contact me over email I might be able to fix a solution for the problem. First, if you are talking about saved session you have constant backup of them by Firefox and you can restore everything for a few days. Second, if any bookmark was really deleted trust me... the addon is not at fault. There's simply no way the addon will ever do that under any circumstances. There's nothing like that. You either delete it or it will be forever stored into Bookmark Menu -> Session Sync folder.

Everything you manually store is in Bookmark Menu -> Session Sync folder... so if data is there... the it should be displayed in the addon as well.
If you're talking about the auto-saved session... that I can't do to much about them. But if you talk about bookmarks session... even if there by any strange reason you have an error. Reinstalling the addon will make it work without any problem because the data is there in the bookmarks and it will never be deleted randomly. Why you can't access the links... I never encounter this error and I don't actually understand why it won't be fixed if you close the panel and open it again because each time the data is requested from the bookmarks and even if there's a small error it will be fixed right after opening it again.

Like I said, if you can, please contact me over email (press the feedback button from the addon menu and you will be redirected to send an email), because I belive that the issues should be fixable. Just giving it 3 starts after using it for an year will not help anyone, not me, not probably not other people because the issues seems quite strange and there are thousands of people that constantly delete session and there's no issue like that so I assume there's something very edge case here.

Update 2:
I'll definitely look more into it. And try to fix it. But trust me, unless I can reproduce this myself, it's impossible to know if what change I do are good or not. So I have somehow to find the cause why it is happening first. I'll try maybe to use a really old PC to see if speed can affect it.

Update:
Well... maybe but again. If one of them works for you doesn't really mean one is flawless and the other one has issues. Also like I pointed you, the fact that things are not saved as they should is not something common or directly a bug from this addon. There can be lots of reasons for it (even other extensions at fault that mess with settings or who knows). If there was a chance for me to understand the bug and create the same issue trust me I would have fixed it long ago. I tried on multiple sistems, different configuration, etc, etc... but I had no chance of repeating the bug. If I can't find the issues it's extremely hard to point to an issue in the code. Also, as much as I look over the code there's not something I find wrong with it. It's really strange. So the fact that MySession works in your case doesn't really tell me anything just as with the fact that this extension doesn't somehow works as it was suppose to. There's something else at fault, most probably. I mean...

The way I save bookmarks is like this... If you have 100 tabs.. then I take each one and tell Firefox
- save the first one at the end, when done... I select the next one and save it ... and so on
How this can fail and turn everything into a mess in the bookmarks... god knows... because that's clearly not what I do. So I bet it's something internal to Firefox, just as what Firefox does on the Firefox Mobile side where it randomizes everything in bookmarks like hell. The order I have on Desktop has nothing to do with now it sees that information in the mobile version. From what I notice, it might order them by access time and not by position or whatever it does.

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I'm really sorry that you have this bug, but trust me that's not something common. As much as I wish to fix it there simply nothing I can find wrong with the code. Also the bug seems to happen only for some users so I don't know if it can be related to the speed of the computer or who knows. The only thing I can think of is if somehow Firefox saves randomly some bookmarks although I specifically send the order and save them one after one on purpose. I really have no clue, but probably I will try to create a second check to make sure that everything was saved as it was suppose to and if there was any problem regarding the order to just order them as they should.
I tried with over 100 tabs multiple times, every single time I try to replicate the issue myself I can't simply find it and it's really hard to fix something that only happens in some specific conditions. Not saying that this is not an issue, just point out that it's really hard to find out why it's happening for some users and for others never.

There are a lot of addons that do similar things yet all of them are somehow different. In this case... the bookmarking system is actually a core feature of the addon. I do understand that it's not perfect but there's no perfect solution. Perfect it's an individual preference and as a developer it's impossible for me to target everything. And I think that's fine, each of us will look for that we think fits better our needs.

That being said, I'm sorry that you consider the bookmarking system a not so good fit for this, but sadly it's a core feature of the product and it's impossible to change. If I would do that ever it will definitely be a different addon. I believe that that Sync-ing with Dropbox or other solutions might be another good feature but at the same time without offering a cross-browser solution it can be quite pointless. Why there's no Chrome port of this addon. Simply because I don't have time to write it. I have so many features waiting on the list to be implemented into this addon, but at the same time the Chrome version is not so important for me as a developer. This addon was built for Firefox and I continue to do so as a thanks for the Mozilla community. It's for Firefox and I don't think I really want to provide a Chrome version because I don't want to promote a different browser. And of course... competing with Session Buddy is quite pointless at this moment. That doesn't mean I won't do this ever but for the moment I clearly have no motivation to do so.

Ultimately, the addon can't be perfect for everyone, but it can be almost perfect for those that find it useful as it is. Thanks for considering using it.

Hi,
1) I don't really get what's with that specific number in your case. There are users that even restore 1000 tabs. I tried with a few hundreds and is working flawlessly. Do you want to just restore them (lazy loading) or even load them. I would recommend to have lazy loading activated because otherwise opening over 100 tabs won't be an addon issue but most probably will depend on hardware configuration and if the browser can cope with that. Any chance you might be able to explain me a little in more details what exactly it is happening in your case (you can do so over email (use the Feedback Button from the addon menu) or by submitting a Github issue (https://github.com/ReDEnergy/SessionSync/issues))

2) Sadly, as much as this would be considered a great feature, that's clearly something I never intended to do with this addon because it's simply not possible to do with Bookmark storage. Didn't know that Session Buddy does this. I just wonder, let's say I would keep the history somehow... but for how long exactly, you can end up thousands of history pages for each tab if you re-save for example a certain session again and again, and again. You clearly need to stop somewhere because otherwise I can see a lot of problems... (performance wise) Of course... for example this can be configurable so that I can set it with a depth of 10 pages, and if the users wants more he can set whatever number he wishes but with a clear warning that doing so it can affect performance.
Can I do something like this... with some hacks I might be able to do (not sure right now though)... but not really if I really should implement such a feature since it can affect the performance for 99.99% of users that most probably don't need such thing. Probably only if it's a feature disabled by default and you can activate it. I wanted to do something similar a while ago but only for seeing a graphical representation of history, not to save it as well. For what you're asking I can definitely say that is clearly not something easy to implement, but I have some other features that once implemented might prove to help me to do such thing, but I really can't promise anything.

Thanks for feedback.

For the update (2019/08)

Sorry for the issue with History. There was a bug in the previous version (that only happened in some specific conditions where everything in the history would be deleted) and somehow it seems that some users continue to have that. There's seems to be an strange incompatibility that somehow I can't replicate myself to find out the bug. I'm pretty sure that if you reinstall the addon everything will be working flawlessly again and probably you won't have any more problems. Everything you saved as bookmarks is safe so you can uninstall and install it without any issue (by doing that you only lost History but since it's already blank it is not a problem.)

I just noticed this update by chance because I observed that one 5 star rating disappeared. Sadly the review section is really stupid and nobody is ever notified of an update so please it you ever have other problem it's better to send me a mail through the feedback button. I guarantee you that there's a great chance to solve everything by discussing than just updating the review (of course you can do that as well but it doesn't really fix anything and that's not really helping anyone, bugs can remain in the app and you don't really fix the issue)

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Thanks for the review. If I'm not wrong and you just changed the rating from 4 stars to 5 stars, I really appreciate that. It's really hard to try to meet everyone's expectation but I hope that in time by adding new features things will only get better.
I might be able to add a form of syncing for the auto-saved history sessions in the feature, but that only if the API is able to understand different devices (at this moment I can't figure out a solution for this) because otherwise one device will overwrite the others and that would clearly not be something desirable.
For bookmarks sync service - Firefox account is the best option.