Firebug shows error "_11 is undefined"

Question

Actually that's it. What does this error mean? I've googled on it, but found nothing. This error appears in firebug console after the page is loaded, or when i click on tabs. It does not prevent the execution of another JavaScript code, but the nature of it is mysterious for me.

Answer 1

"_11" sounds like a JavaScript variable or function that has been minimized.

Answer 2

Somewhere in your code or the JS framework you use, a variable pointer _11 is called but nothing is assigned to it. Hence javascript gives undefined.

It sound indeed, like mmattax says, as a minified javascript variable name. It probalby references a variable in your javascript that is not defined.