I have a submit button at the end of the form.
I have added the following condition to the submit button:
onClick="this.disabled=true;
this.value='Sending…';
this.form.submit();"
But when it moves to the next page, the parameters did not pass and null values are passed.
You should first submit your form and then change the value of your submit:
onClick="this.form.submit(); this.disabled=true; this.value='Sending…'; "