While unsaving a question, I get an error message saying "An error occurred" [duplicate]

Since last couple of days, I am facing an error while unsaving a question.
On question, if I try to unsave a question by clicking a bookmark like button below downvote button, it does not work and shows the error "An error occurred".

Earlier I thought this might be something temporary and neglected; but this is consistent.

Saving the question works fine. Unsaving the question from "Saves" tab also works fine.

Another interesting observation is that, if I open a question -> save it -> immediately unsave it. It works.

Also, it seems only with me (or may be very few others), because, I asked about this on SOCVR and no one said they do have this issue.

Steps to reproduce:-

1. Open a previously saved question from "Saves" tab.
2. Click the "Save/Unsave" button below "downvote" button.
3. I get the red popup message saying "An error occurred".

Environment:-

1. Browser is Chrome latest version
2. Windows 10 64 bit.
3. I have created 2 saves lists addition to the default; total 3.