I'm currently suffering from this in 2018.1.5f1. A restart briefly allows me to rename objects through contrext menu or F2, but only for a short while.

I can confirm that all these issues are related to gameobjects in the scene that have layout group scripts on them. Mine has horizontal layout group. When I disable all objects with such components, the renaming issues all get resolved.

In fact, pressing any non-character keys while renaming will escape as if one pressed enter. Caps-lock, Ctrl, shift, they all escape the renaming. This started when I changed layout as a fix to not even being able to start renaming. This is slightly better although it prevents me from using
capitals

DIGITALSTATE's solution worked, changed layout and then suddenly renaming works but not quite: Now I can't use shift in the renaming because shift started to act like return so as soon as I press shift while renaming, it escapes. All in all, this bug has been around for years with no real fix.

I had this same problem in 2018.1.0f2 I found a easy fix, simply change your layout view in the window tab and everything works perfect.

Not fixed

Hey guys,
Never posted before and i am using the beta version 2017.3 and i have the same bug.

Heres the good news.
I think i found a fix.

Make a new game object (For sake of arguement)
Select it
HOLD F2 in and Left click the field
Rename and press return.

After doing this i was able to rename by F2 and by the menu again.

Same here!!!1 version 2017.2.0f3

Why is this marked fixed? I've been working on a project in Unity 2017.2 for a month and then out of nowhere this bug kicked in. All of a sudden I can't rename anything in Hierarchy, whether I left click on the name once or I right click and choose 'Rename', none of these usual processes work. Restarting Unity doesn't help either. Only workaround is to use the name field in the inspector, but I don't think a workaround is considered to be a fix for a bug.

2017.2.0f3 still here...