Hello Thomas,

such error has typically one from two reasons: 1) you downloaded jqGrid without including “form editing” module (see jqGrid download page) 2) you use wrong order of JavaScript files inserted in the page. To verify the first one probelm you can open jquery.jqGrid.min.js file in the text editor and search in the comment at the beginning of the file for grid.formedit.js after the text “Modules:“. In all cases the error is probably not in the part which you posted, but in for example the HTML code which shown the order of files included.

Best regards
Oleg