I've run into the same issues when upgrading our Vuforia Master Project. We keep a master on the asset server as we have written a few extension scripts and this (should) allow us to update vuforia into this project, check changes using the diff, before repackaging into our own. 

Why was it decided to move so many of the original source files into .dll?

Thanks, that would probably be a good idea.  And yes, it built after deleting the scripts folder and readding (with auto refresh off).  Next experiemnt is to see if I can surgically upgrade a project removing the unnecessary scripts and importing the new package.  Though in most cases I can imagine deleting the scripts folder to work well enough.

Cheers, thanks again for you help.

Thanks for the feedback, and please update the thread when you know whether the build is running properly. I think we'll need to extend the migration docs.

Okay, I'm trying a build now.  I also created a project from scratch so I could see what changed between versions.

I tried deleting ITrackableEventHandler but it was a little like pulling on a loose thread.  Ran a diff on both directories to get a sense for how much difference there was between the two (is this listed somewhere else?)  If not I'll include it here so anyone interested can extract the files that might be causing the conflicts.

I did try a version where I just deleted the whole scripts folder and reimported, that seems to have worked but I haven't tried a full build yet to see if it's in tact.  If anyone else stumbles across these directions be sure to disable the auto-refresh in preferences or else you could end up in a very bad place.

See if you have an ITrackableEventHandler CS file in you project, and if so remove it.

If that doesn't work, try making a copy of your project, so that you have a backup, delete the Qualcomm Augmented Reality / Scripts folder, and then re-import the VP sample or the extension. 

I think that you're running into a collision in the definition of these classes, but Unity isn't recognizing the duplicates because the new ones are defined in the DLL.

Is this the only error you're still seeing?

I had upgraded using the unity extension package alone.  

I've imported the VideoPlayback sample package and the error persists.

Are there any other files that could be causing a conflict I should be removing?  I can't see if there is a connection between these errors and the new code changes.

Your extension name is correct. Try importing the full video sample into your project to see if it will rectify that error. 

Had you upgraded using the extension unitypackage alone?

The VP sample is now packaged with the rest of the Unity samples here - https://developer.vuforia.com/resources/sample-apps

Oh okay, thanks!

Do you have a UnityExtensions.dll in Qualcomm Augmented Reality / Scripts / Internal?

The VP sample is now packaged with the rest of the Unity samples here - https://developer.vuforia.com/resources/sample-apps

Do you have a UnityExtensions.dll in Qualcomm Augmented Reality / Scripts / Internal?

.. and is the following the DefaultTrackableEventHandler.cs that you have in your project. 

/*==============================================================================
Copyright (c) 2010-2013 Qualcomm Connected Experiences, Inc.
All Rights Reserved.
Confidential and Proprietary - Qualcomm Connected Experiences, Inc.
==============================================================================*/

using UnityEngine;

/// <summary>
/// A custom handler that implements the ITrackableEventHandler interface.
/// </summary>
public class DefaultTrackableEventHandler : MonoBehaviour,
                                            ITrackableEventHandler
{
    #region PRIVATE_MEMBER_VARIABLES
 
    private TrackableBehaviour mTrackableBehaviour;
    
    #endregion // PRIVATE_MEMBER_VARIABLES



    #region UNTIY_MONOBEHAVIOUR_METHODS
    
    void Start()
    {
        mTrackableBehaviour = GetComponent<TrackableBehaviour>();
        if (mTrackableBehaviour)
        {
            mTrackableBehaviour.RegisterTrackableEventHandler(this);
        }
    }

    #endregion // UNTIY_MONOBEHAVIOUR_METHODS



    #region PUBLIC_METHODS

    /// <summary>
    /// Implementation of the ITrackableEventHandler function called when the
    /// tracking state changes.
    /// </summary>
    public void OnTrackableStateChanged(
                                    TrackableBehaviour.Status previousStatus,
                                    TrackableBehaviour.Status newStatus)
    {
        if (newStatus == TrackableBehaviour.Status.DETECTED ||
            newStatus == TrackableBehaviour.Status.TRACKED ||
            newStatus == TrackableBehaviour.Status.EXTENDED_TRACKED)
        {
            OnTrackingFound();
        }
        else
        {
            OnTrackingLost();
        }
    }

    #endregion // PUBLIC_METHODS



    #region PRIVATE_METHODS


    private void OnTrackingFound()
    {
        Renderer[] rendererComponents = GetComponentsInChildren<Renderer>(true);
        Collider[] colliderComponents = GetComponentsInChildren<Collider>(true);

        // Enable rendering:
        foreach (Renderer component in rendererComponents)
        {
            component.enabled = true;
        }

        // Enable colliders:
        foreach (Collider component in colliderComponents)
        {
            component.enabled = true;
        }

        Debug.Log("Trackable " + mTrackableBehaviour.TrackableName + " found");
    }


    private void OnTrackingLost()
    {
        Renderer[] rendererComponents = GetComponentsInChildren<Renderer>(true);
        Collider[] colliderComponents = GetComponentsInChildren<Collider>(true);

        // Disable rendering:
        foreach (Renderer component in rendererComponents)
        {
            component.enabled = false;
        }

        // Disable colliders:
        foreach (Collider component in colliderComponents)
        {
            component.enabled = false;
        }

        Debug.Log("Trackable " + mTrackableBehaviour.TrackableName + " lost");
    }

    #endregion // PRIVATE_METHODS
}

Thanks for getting back so quickly, would love to get this sorted today.

I deleted TrackableBehaviour and now am getting the following error:

The TrackableBehaviour class is now in the UnityExtensions DLL. Check to see if you still have the old version as a CS file, and if so remove it.

The VideoPlaybackBehaviour should be in the Vuforia Video Playback / Scripts folder, which is imported w/ the VP sample.