PHP - How To Add My Own Php Code Files To Wordpress Files

array:
[SomePath/test.php] = "All In this php file is being read by a new smart function!";
[SomePath/Weird/hello.txt = "Hello world. This is me and im just trying to get some help!";

So far I have managed to create an upload process which uploads a picture, updates the database on file location and then tries to upload the db a 2nd time to update the Thumbnails file location (i tried updating the thumbnails location in one go and for some reason this causes failure)

But the main problem is that it doesn't upload some files

Here is my upload.php

<?php
include 'dbconnect.php';

$statusMsg = '';

$Title = $conn -> real_escape_string($_POST['Title']) ; 
$BodyText = $conn -> real_escape_string($_POST['ThreadBody']) ; 
	 

// File upload path
$targetDir = "upload/";
$fileName = basename($_FILES["file"]["name"]);
$targetFilePath = $targetDir . $fileName;
$fileType = pathinfo($targetFilePath,PATHINFO_EXTENSION);
$Thumbnail = "upload/Thumbnails/'$fileName'";

if(isset($_POST["submit"]) && !empty($_FILES["file"]["name"])){
    // Allow certain file formats
    $allowTypes = array('jpg','png','jpeg','gif','pdf', "webm", "mp4");
    if(in_array($fileType, $allowTypes)){

        // Upload file to server
        if(move_uploaded_file($_FILES["file"]["tmp_name"], $targetFilePath)){

            // Insert image file name into database
            $insert = $conn->query("INSERT into Threads (Title, ThreadBody, filename) VALUES ('$Title', '$BodyText', '$fileName')");
            if($insert){
               $statusMsg = "The file ".$fileName. " has been uploaded successfully."; 

		$targetFilePathArg = escapeshellarg($targetFilePath);
		$output=null;
		$retval=null;
		 //exec("convert $targetFilePathArg -resize 300x200 ./upload/Thumbnails/'$fileName'", $output, $retval);
		 exec("convert $targetFilePathArg -resize 200x200 $Thumbnail", $output, $retval);
		echo "REturned with status $retval and output:\n" ; 
		if ($retval == null) { 
		echo "Retval is null\n" ;
		echo "Thumbnail equals $Thumbnail\n" ; 
		}

            }else{
                $statusMsg = "File upload failed, please try again.";
            } 
        }else{
            $statusMsg = "Sorry, there was an error uploading your file.";
        }
    }else{
        $statusMsg = 'Sorry, only JPG, JPEG, PNG, GIF, mp4, webm & PDF files are allowed to upload.';
    }
}else{
    $statusMsg = 'Please select a file to upload.';
}

//Update SQL db by setting the thumbnail column to equal $Thumbnail
$update = $conn->query("update Threads set thumbnail = '$Thumbnail' where filename = '$fileName'");
            if($update){
               $statusMsg = "Updated the thumbnail to sql correctly.";
		echo $statusMsg ;  } 
else 
{ echo "\n Failed to update Thumbnail. Thumbnail equals $Thumbnail" ; } 


// Display status message
echo $statusMsg;
?>

And this does work on most files however it is not working on a 9.9mb png file  which is named "test.png" I tested on another 3.3 mb gif file and that failed too?

For some reason it returns the following

Updated the thumbnail to sql correctly.Updated the thumbnail to sql correctly.

Whereas on the files it works on it returns

REturned with status 0 and output: Retval is null Thumbnail equals upload/Thumbnails/'rainbow-trh-stache.gif' Failed to update Thumbnail. Thumbnail equals upload/Thumbnails/'rainbow-trh-stache.gif'The file rainbow-trh-stache.gif has been uploaded successfully.

Any idea on why this is?

Greetings to all!

Newbie here, I just signed up this morning. I have an issue with a code I have been using for several years with multiple files/directories. Until recently all of the files have worked flawlessly. Now I have one file in a directory that does not display the text I which I am attempting to call up and it was working until recently.

As stated above I have the same code in multiple directories and files and it works flawlessly in all files except for the one. I have spent a few hours attempting to remedy the situation with no success. I have looked at the source code for the errant file and that shows the text to be displayed but it is not displayed in any browser on several computers, whether Windows or Mac OSX. I even went so far as to delete the directory the file was in and re-uploaded the entire directory from a backup that is 2 or 3 years old, no change. I copied the entire coding from a working file with the same coding, deleted all the coding in the errant file and pasted the working coding into the errant file. - no change

I have attached screen shots of the coding in errant file and one of many other files that work flawlessly with the php code that is involved highligted. Also attached are the browser page source files for the same errant and working files. The screen shots in order are errant file code, working file code, errant file source, and working file source.

Every file with the same code as the errant one work flawlessly except for the errant one, and I have 11 files to be displayed on my website at https://TheLoveOfGod.org They are all listed under the Devotionals menu button except for one which is displayed on the home page. I have absolutely no training in web design, I am self taught. I began by hand typing html coding over 30 years ago and am now using Word Press with Elementor . I do not understand why this is happening. Can any of you offer assistance to resolve this. I thank you in advance for your assistance.

Respectfully,
dan