Textify

Textify is a tiny utility that enables you to grab text from message dialog boxes and windows that feature content that cannot be copied with the standard methods.

Comes with a minimalistic and barebones UI

The setup is quick, uneventful and does not require any special attention from your part, especially since all you need to do is decompress the archive in the desired location on your local drives. Upon launch, you come face to face with a tiny window that displays the available settings of the application.
It is worth mentioning that the program cannot be minimized to tray, a feature that is not critical, but would be convenient when you are working on a project that entails keeping several windows open. On the other hand, if you are looking for more convenience, then you should know that the tool can be launched with a hidden window (-hidewnd command line switch).

Allows you to configure a copy hotkey

As previously mentioned, the UI consists of a settings window that enables you to set the desired key combination you prefer to copy text from various window screens or error messages you come across. Therefore, you can copy text using one your mouse (left, right or middle button) solely or you can create a key combination with Control, Alt and the Shift keys.
Even though it allows you to use all three keys to create shortcuts that you can easily remember,  it would have been pleasant and helpful if the utility enabled you to set your own hotkeys. This way you can be sure that you do overlap the hotkeys with others you assigned to an app you are constantly using.

A tool that helps you grab text that cannot be copied

All in all, if you are looking for a tool to help you cop the error message from various window screens so that you can paste it into a search engine, and perhaps find a solution to your issues, then Textify might be the utility to lend you a hand.