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

1 vote305 views1 answer
Js cannot copy entire object
Html
0 vote329 views1 answer
How to create bold text in html
Html
5 votes328 views1 answer
Html how to add jquery
Html
16 votes358 views6 answers
Striped table bootstrap
Html
-3 votes332 views1 answer
Class#
Html
2 votes308 views2 answers
Add google search bar to our website in html
Html
2 votes339 views1 answer
Suggestion none input
Html
4 votes340 views6 answers
Aos library
Html
1 vote319 views3 answers
Bootstrap cards with image on the right side
Html
0 vote312 views1 answer
Telto
Html