How to cancel autocomplete in Visual Studio 2015 by pressing "Space"?

If you run Resharper, check Resharper > Options.

Under Environment > IntelliSense > Completing Characters.

Uncheck "Complete on space" for the desired language.

To disable autocomplete you can use:

Edit->IntelliSense->Toggle Completion Mode(Ctrl+Alt+Space)

This will also disable it for all characters. This suits me but may not be exactly what you are looking for, VS2013 allowed you to select which characters and specifically Space I'm not sure why this was removed.

To Disable brace completion:

Tools->Options->Text Editor->C#->General->Automatic Brace Completion

There is a way to turn off this particular behavior in Visual Studio 2015, while leaving the completion fully functional. However, this works only with some languages. In options:

Text Editor -> [your language] -> IntelliSense -> 'Only use Tab or Enter to commmit'

Worked for me for the Java Script editor, but there is no equivalent to C# (where I personally don't find this feature as annoying.

The Escape key will cancel intellisense and allow you to continue typing anything you want without interferences. Just tried it on VS2013 to confirm.

As to the "{" being closed with a "}", this is usually caused by an extension such as Resharper, MS PowerTools, or similar.