Cannot login properly after forum update

[Aleksei]

Hi! Need your help.
I've just updated the forum to the latest version (1.15.x). And after that when I login on the site and enter account credentials correctly I'm not redirected to the forum page, but instead, I get an error in console:

Cannot read property 'user' of undefined

The issue looks like the one described here: https://github.com/NodeBB/NodeBB/issues/3489
But, in my case, removing node_modules folder and reinstalling all dependencies didn't help.
Additionally, I cannot reach /admin page even when I'm authorized.

Please, help. Couldn't find any solutions online.

[Aleksei]

Ok, the problem was solved. But I'm not sure how exactly.
After I wrote this post I noticed that the latest version of NodeBB is 1.16.x. But while upgrading the forum i switched to 1.15.x branch (I thought that was the latest).
After that, I used ./nodebb upgrade command. Maybe this was the issue? Maybe, I switched to the previous version branch, but installed the latest version of files with the "upgrade" command? — I don't really know. But when I switched to 1.16.x and upgraded the forum again, then it worked as expected. The forum now works fine.