LESS CSS Compiler Error, Cannot find function toCSS in object

[Seanom]

I have a fairly clean install of bootstrap but get the following error when trying to compile a main.less file

LESS CSS Compiler Error
         main.less: Syntax Error: Cannot find function toCSS in object [object Object]. (line -1, column -1) near
         * Bootstrap v2.2.0

If I remove the the top comment, error changes to

LESS CSS Compiler Error
         main.less: Syntax Error: Cannot find function toCSS in object [object Object]. (line -1, column -1) near
         // CSS Reset

[AnYaran]

how to solve??

[a-x-]

// Excuse me, I speak broken English.

I have similar trouble. For example

.preview-wrapper {
  width: e(calc(98vw - 115px));
}

==>

.preview-wrapper {
  width: [object Object];
}

[bluemoehre]

I saw the same. But for me this is additionally a wrong usage of the escape function. As documentation says, you have to pass string:

String Functions

e (CSS escaping, replaced with ~"value" syntax.)

Parameters: string - a string to escape. Returns: string - the escaped string, without quotes.