Got warning while uploading video file in PHP but not image or audio file [duplicate]

i got warnings when i upload a video file in PHP

This is my HTML code:

<form method=”post” action=”post.php” class=”box” enctype=”multipart/form-data”>

<textarea rows=”5″ cols=”35″ name=”message” placeholder=”content”>

<input type=”file” name=”mediaFile”>
button type=”submit”>Post
</form>

These are the warnings:

`Warning: POST Content-Length of 81138635 bytes exceeds the limit of 41943040 bytes in Unknown on line 0

Warning: Undefined array key “message” in C:xampphtdocspost.php on line 15

Warning: Undefined array key “mediaFile” in C:xampphtdocspost.php on line 24

Warning: Trying to access array offset on value of type null in C:xampphtdocspost.php on line 24`

why i did not get these warnings when i successfully upload a image or audio file in the server?