Javascript Error: 11233 Content-Length mismatch

Today I got a error in fiddler:

Failed to obtain request body. System.IO.InvalidDataException The request body did not contain the specified number of bytes. Got expected

11233 Content-Length mismatch: Request Header indicated 7,431 bytes, but client sent 0 bytes.

I goole all key words on web, but no any clues to root cause. Here is the script:

function ShowRatePopUP() {
ratePopUpLinkButton = document.getElementById(ratePopUpLinkButtonId);
if (ratePopUpLinkButton) {
ratePopUpLinkButton.click();
}
}

This is a simple function to access on server function "ratePopUpLinkButton.click();" , but why Content-Length in header is different with that client sent?

The root cause is "Response Confiliction". ShowRatePopUP() didnt return false, that inform the server side it will also need to request to server side. But ratePopUpLinkButton.click(); is also request to server side. Therefore just return false, fixed.

function ShowRatePopUP() {
ratePopUpLinkButton = document.getElementById(ratePopUpLinkButtonId);
if (ratePopUpLinkButton) {
ratePopUpLinkButton.click();
}

return false;
}