TypeError: Illegal invocation

Your datatype is not JSON, it’s a FormData. And for jQuery to send a FormData, it needs…
$.ajax({
    type: "POST",
    url: 'signin2.php',
    data: formData,
    processData: false, //add this
    contentType: false, //and this
})

Similar codes

201 votes470 views5 answers
Blank space html
Html
15 votes326 views2 answers
Html datetime format
Html
54 votes323 views6 answers
How to change font color in html
Html
3 votes330 views2 answers
Html 2 classes
Html
0 vote347 views1 answer
Font jrxml
Html
11 votes305 views2 answers
Html input date format
Html
0 vote326 views1 answer
Twig html to markdow
Html
-2 votes318 views1 answer
W3c
Html
-2 votes262 views1 answer
How to onclick function in php
Html
1 vote340 views1 answer
Bootstrap textarea width
Html