title: Cannot publish individual customization packages in Acumatica
body: <p>I'm having a strange problem on my development workstation. I can no longer publish <strong>ANY single</strong>  customization package within Acumatica using the Project Browser window. But strangely, I can still publish <strong>ALL packages</strong> without issue from the main Customization Project screen (SM204505). This makes for an awkward development workflow.</p>
  <p>This behavior started after I upgraded Visual Studio between minor versions: 15.9.17 to 15.9.28.</p>
  <p>Here's a screenshot of the error in the Project Browser:</p>
  <p><a href="https://i.stack.imgur.com/Tf24C.png" rel="noreferrer"><img src="https://i.stack.imgur.com/Tf24C.png" alt="enter image description here" /></a></p>
  <p>The 505 error trace log in Event Viewer:</p>
  <pre><code>Exception information:
      Exception type: NullReferenceException
      Exception message: Object reference not set to an instance of an object.
     at PX.Customization.CstValidationProcess.ProcessRequest(HttpContext context) in C:\Bld2\AC-FULL2019R113-JOB1\Sources\NetTools\PX.Web.Customization\Publish\CstValidationProcess.cs:line 89
     at ASP.controls_publish_aspx.ProcessRequest(HttpContext context) in c:\AcumaticaSites\TemporaryAspFiles\2019r1\2019r1\e88eaed9\5694cb3e\App_Web_publish.aspx.cc671b29.dndzcldh.0.cs:line 0
     at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
     at System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step)
     at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean&amp; completedSynchronously)
  
  Request information:
      Request URL: http://localhost/2019r1/Controls/Publish.aspx?compile=true&amp;callback_id=0&amp;suffix=40060f45-d71e-4139-9922-bb678ddbdfb1
      Request path: /2019r1/Controls/Publish.aspx
      User host address: ::1
      User: admin
      Is authenticated: True
      Authentication Type: Forms
      Thread account name: IIS APPPOOL\DefaultAppPool
  </code></pre>
  <p>I'm not sure what to try to resolve this. Any ideas?</p>