How to disable error squiggles in C++ code in VS Code?

The straightforward thing works

What you said you did works for me in VSCode 1.37.1.

Before, with defaults:

Changing the setting:

After:

Excerpt of settings.json:

{
    ....
    "C_Cpp.errorSquiggles": "Disabled"
}

Hypotheses about why it did not work for you

There is another settings.json attribute called C_Cpp.default.enableConfigurationSquiggles. Might you have accidentally changed that one?

Is "C_Cpp: Intelli Sense Engine" set to "Default"? It should be (rather than "Tag Parser") in order to disable squiggles.

Maybe the syntax error you have is different somehow?

For ease of reproduction, it would help to see your settings.json, c_cpp_properties.json, and an example of erroneous syntax with squiggles.

Currently, there is no settings to turn the error decorations off but some language extensions implement their own solutions.

If you are looking for a language agnostic solution, you can make the squiggly lines transparent by adding following setting to general settings or workspace settings file.

"workbench.colorCustomizations": {
  //                                ↓↓
  "editorError.foreground": "#00000000"
}

For a specific language:

"workbench.colorCustomizations": {
  "[jsonc]": {
    //                                ↓↓
    "editorError.foreground": "#00000000"
  }
}

Please note that we use 8-digit hex value, the first six is not important but last two should be zero to make the color transparent.

Here is how you can do it programmatically in an extension:

workspace.getConfiguration('workbench').update( 'colorCustomizations', {
    "editorError.foreground": "#00000000",
});

just go to command palette (ctrl + shift + P) and then search C/C++ enable error squiggles and select that. Done