On clicking the submit button of a form, it's not responding

Form submit button is not responding even though I have specified the action, in the form action field.

<div class="container">
<form action="php/record.php">
<h3>Enter the following details :</h3>
<form autocomplete="off" action="">
<div class="autocomplete" style="width:300px;">
<label for="school">School :</label> <br>
<input id="school" type="text" name="School" placeholder="Enter School" required>
</div>
</form>
<br>
<form autocomplete="off" action="">
<div class="autocomplete" style="width:300px;">
<label for="school_ID">School ID :</label> <br>
<input id="school_ID" type="text" name="School_ID" placeholder="Enter School ID" required>
</div>
</form>
<br>
<label for="class">Class :</label>
<select name="Class" id="class">
<option value="I">I</option>
<option value="II">II</option>
<option value="III">III</option>
<option value="IV">IV</option>
<option value="V">V</option>
</select>
<label for="sec">Sec : </label>
<select name="sec" id="sec">
<option value="A">A</option>
<option value="B">B</option>
<option value="C">C</option>
<option value="D">D</option>
</select>
<br><br>
<label for="Film_1">Film 1 :</label> <br>
<input id = "Film_1" type= "text" placeholder="Enter film 1" name="Film_1" required>   
<br>
<br>
<label for="Film_2">Film 2 (if applicable) :</label><br>
<input id = "Film_2" type="text" placeholder="Enter film 2" name="Film_2">
<br>
<br>
<label for="Film_3">Film 3 (if applicable) :</label><br>
<input id = "Film_3" type="text" placeholder="Enter film 3" name="Film_3">
<br>
<br>
<button id="submit_btn" type="submit">Submit</button>
<input name="Picture" type="file" onchange="readURL(this)" accept="image/*">
</form>
</div>    
</body>

Please suggest me where I'm going wrong in my code as nothing is happening on clicking the submit button. I want to redirect to another page i.e. record.php on clicking submit

> <button id="submit_btn" type="button">Submit</button>

That isn't a submit button.

A submit button has type="submit" (or no type attribute at all as submit is the default value).

type="button" is used for buttons which has no default behaviour (i.e. when you want to add behaviour using JavaScript).

> <form action="php/record.php">
> <h3>Enter the following details :</h3>
>
> <form autocomplete="off" action="">

Forms may not be nested. Write valid HTML. Remove the extra form.

You did not specify a submit button.

Change

<button id="submit_btn" type="button">Submit</button>

To

<button id="submit_btn" type="submit">Submit</button>

Also you have several forms nested, which isn't allowed and can also cause your browser to behave unexpected

You have some mistakes in the code.
you can use that code.

<div class="container">
<form action="php/record.php">
<h3>Enter the following details :</h3>
<div class="autocomplete" style="width:300px;">
<label for="school">School :</label> <br>
<input id="school" type="text" name="School" placeholder="Enter School" required>
</div>
<br>
<div class="autocomplete" style="width:300px;">
<label for="school_ID">School ID :</label> <br>
<input id="school_ID" type="text" name="School_ID" placeholder="Enter School ID" required>
</div>
<br>
<label for="class">Class :</label>
<select name="Class" id="class">
<option value="I">I</option>
<option value="II">II</option>
<option value="III">III</option>
<option value="IV">IV</option>
<option value="V">V</option>
</select>
<label for="sec">Sec : </label>
<select name="sec" id="sec">
<option value="A">A</option>
<option value="B">B</option>
<option value="C">C</option>
<option value="D">D</option>
</select>
<br><br>
<label for="Film_1">Film 1 :</label> <br>
<input id = "Film_1" type= "text" placeholder="Enter film 1" name="Film_1" required>   
<br>
<br>
<label for="Film_2">Film 2 (if applicable) :</label><br>
<input id = "Film_2" type="text" placeholder="Enter film 2" name="Film_2">
<br>
<br>
<label for="Film_3">Film 3 (if applicable) :</label><br>
<input id = "Film_3" type="text" placeholder="Enter film 3" name="Film_3">
<br>
<br>
<input name="Picture" type="file" onchange="readURL(this)" accept="image/*">
<button id="submit_btn" type="submit">Submit</button>
</form>
</div>