Question: It is my first time using PHP. I am using XAMPP on a mac.

MySQL, Apache, and localhost:8080 are all working right now.
I created this file called test.php and saved it inside lampp/htdocs:

```
<!DOCTYPE html>
<html lang="en">
<head>
  <title>Connection</title>
</head>
<body>

<?php
  $servername = "localhost:8080";
  $username = "root";
  $password = "root";

  // Create connection
  $conn = mysqli_connect($servername, $username, $password);

  // Check connection
  if (!$conn)
  {
    die("Connection failed: " . mysqli_connect_error($conn));
  }
  else
  {
    echo "Connected successfully";
  }
?>

</body>
</html>

```

However, when I go to localhose:8080/test.php a blank page opens but nothing shows up

Answer: 
Okay, partially my bad.
I did re-compile the **EMPTY** sample project and found that despite the compiler error, the solution does build.

```
1>------ Rebuild All started: Project: Microdesk.BIMrxCommon.Infrastructure, Configuration: Debug2020 Any CPU ------
1>  Microdesk.BIMrxCommon.Infrastructure -> C:\Work\Microdesk.BIMrx\bin\Debug2020\Microdesk.BIMrxCommon.Infrastructure.dll
2>------ Rebuild All started: Project: Microdesk.BIMrxCommon.DbApp, Configuration: Debug2020 Any CPU ------
2>C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(1720,5): error : Internal MSBuild error: Non-CrossTargeting GetTargetFrameworks target should not be used in cross targeting (outer) build
2>  Microdesk.BIMrxCommon.DbApp -> C:\Work\Microdesk.BIMrx\bin\Debug2020\Microdesk.BIMrxCommon.DbApp.dll
========== Rebuild All: 2 succeeded, 0 failed, 0 skipped ==========

```

**BUT** if you try to USE anything from the Infrastructure project in the referencing DbApp project then the Solution will NOT compile

```
Rebuild started...
1>------ Rebuild All started: Project: Microdesk.BIMrxCommon.Infrastructure, Configuration: Debug2020 Any CPU ------
2>------ Rebuild All started: Project: Microdesk.BIMrxCommon.DbApp, Configuration: Debug2020 Any CPU ------
2>C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(1720,5): error : Internal MSBuild error: Non-CrossTargeting GetTargetFrameworks target should not be used in cross targeting (outer) build
2>C:\Work\Microdesk.BIMrx\BIMrxCommon\Microdesk.BIMrxCommon.DbApp\DerivedClass.cs(1,29,1,4
): error CS0234: The type or namespace name 'Infrastructure' does not exist in the namespace 'Microdesk.BIMrxCommon' (are you missing an assembly reference?)
2>C:\Work\Microdesk.BIMrx\BIMrxCommon\Microdesk.BIMrxCommon.DbApp\DerivedClass.cs(5,33,5,42): error CS0246: The type or namespace name 'BaseClass' could not be found (are you missing a using directive or an assembly reference?)
========== Rebuild All: 1 succeeded, 1 failed, 0 skipped ==========

```

I did upload a second sample project named "Microdesk.BIMrx (2).zip" to the previous OneDrive directory
When I test your issue in your side, I did not face the same behaviors as you described. So I guess that there is some issues on your current vs environment due to the update. And maybe the update broke some tools of VS.

[![enter image description here](https://i.stack.imgur.com/odZR7.png)](https://i.stack.imgur.com/odZR7.png)

So please try the following steps to troubleshoot it:

**Suggestions**

**1)** disable any third party installed extensions under **Extensions**-->**Manage Extensions**-->**Installed**

**2)** close VS, delete `.vs` hidden folder, every `bin` and `obj` folder of your project.

and also delete all cache files under `C:\Users\xxx(current user)\AppData\Local\Microsoft\VisualStudio\16.0_xxx\ComponentModelCache`

**Then**, restart VS to test again.

**3)** or create a new project and then migrate the content from the old into the new one to test whether the issue is related to your VS or the special project itself.

**4)** If this does not work, do an initialization operation on your VS.

**Close VS**, delete the whole user folder under `C:\Users\xxx(current user)\AppData\Local\Microsoft\VisualStudio\16.0_xxx` and then restart VS to test again.

**5)** [repair vs](https://learn.microsoft.com/en-us/visualstudio/install/repair-visual-studio?view=vs-2019) from the vs\_installer