Here at Stack Overflow we're migrating many things to .NET Core. Along the way we have to swap out parts that existed in the old .NET world but don't in the new.

Now that we've safely diverged our Enterprise Q3 release (we work on one codebase for easier maintenance and the latest features go to Enterprise too), we can deploy some things we've been working on. Today, that's Entity Framework Core.

A decade ago, Stack Overflow was written on top of a data layer called Linq-2-SQL. It worked well but had scaling issues. We later replaced performance critical paths with a library we wrote called Dapper. But some old paths (mainly where we insert things) remained on Linq-2-SQL. Until today.

We have just deployed a major migration from Linq-2-SQL to EF Core here to meta.stackexchange.com and meta.stackoverflow.com. If all goes well, Stack Overflow will also get a partial tier deploy later today.

Since many have asked: Dapper isn't going anywhere. No Dapper was removed. A few code paths even went to Dapper instead of EF Core as part of the migration.

We need your help

This change affects Posts, Comments, Users, and other "primary" object types in Q&A. We're not asking for a lot of test data to be created on meta here, but if you see something, please say something! You're probably not crazy, it's probably us. If anything looks out of place today, please open a meta issue here, tweet me directly at @Nick_Craver, or ping us in Stack Overflow chat.

The biggest fear with a change like this is any chance of bad data entering the database, so while we've tested this extensively and have done a few test deploys already, we're still being extra cautious with such a central & critical change.

Thanks for helping us with this. If you have questions, I'll answer as best I can!

Update 1 (2018-10-03 19:00 UTC): We have deployed this to one of the 9 Stack Overflow web servers (serving the entire network) and are continuing to monitor for issues.


4 Answers 4


When you upvote a comment, it does light up and increments the score, but after a refresh, it doesn't show you were the one upvoting, and you can vote again, and again, and again. Post voting seems to work correctly.

Oh, Shog9 noticed it too!

  • 13
    I confirm post voting seems ok.
    – Pikoh
    Oct 3, 2018 at 14:43
  • 5
    Tracking this down now - almost have it. Will deploy a fix soon as we nail it. Thanks! Oct 3, 2018 at 14:45
  • Also, I can't undo the comment upvote, even after 1-2 seconds, it says "You can only undo a comment vote within the first 60 seconds!". /cc @NickCraver (should I start a new bug report for this?) Oct 3, 2018 at 14:47
  • @ShadowWizard Indeed. Oct 3, 2018 at 14:48
  • The vote isn't actually recorded, so there's nothing to undo, @shadow ;-)
    – Shog9
    Oct 3, 2018 at 14:48
  • @ShadowWizard that's because there is no vote recorded...we're changing the aggregate and not storing the actual vote. I'm testing a fix locally, then I'll re-normalize all comment scores after this goes out. Linq2SQL magic was evil...and we haven't killed all of it here :) Oct 3, 2018 at 14:49
  • @Shog9 it is recorded, tried now with the first upvote and I do see the comments score on all comments after reloading the page, so where is it coming from? Oct 3, 2018 at 14:49
  • The logic here is essentially, "check for existing vote, if found do nothing; else increment score and store new vote" @shadow. And that very last step is failing.
    – Shog9
    Oct 3, 2018 at 14:52
  • 13
    A fix has been deployed and comment votes have been re-normalized across the metas. Thanks again for the report! Oct 3, 2018 at 15:10

The "site is currently offline for maintenance" was occurring today on several occasions.



I was browsing on SO and found the comments totally broken on an answer to this question: Difference between a Structure and a Union

I don't know if this is caused by the change, but thought I would let you know in case.

enter image description here

  • What browser are you using?
    – Shog9
    Oct 10, 2018 at 2:01
  • @Shog9: I'm on the latest Firefox (I don't know the version, could be 58 or 60). I can't reproduce the error now though.
    – hat
    Oct 10, 2018 at 5:36

Updating comments : Updated comments starting with "@" not saved to database?.

I was trying to update a comment. Most of the time i start a comment with "@Name :", but I forgot this, so I tried to update the comment with "@Name :". When I saved nothing happened. I tried this a few times. Same result. Then I decided to drop the @ and I tried to update my comment with "Name :". This updated comment was saved correctly to your database.

  • 1
    No bug and not related to the .NET change: meta.stackexchange.com/questions/97098/…. Oct 11, 2018 at 12:18
  • 1
    Thanks, I understand now, but If you don't know that this feature exists it makes no sense.
    – JRB
    Oct 11, 2018 at 12:45
  • 1
    Well, like with many other things, if one wonders what happened or why, they can come to the meta site and look for it, or post a bug report. :) Oct 11, 2018 at 13:08
  • 1
    That said, I'd support a feature request asking to add a small notification when comment is auto edited to remove the post author name. Oct 11, 2018 at 13:09
  • I support this feature request
    – JRB
    Oct 11, 2018 at 14:19

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