Unity5 upgrade invalid serialized file version

Hello.

I recently upgraded a project from Unity4 to Unity5.

This project has streamed assets (3d models that are too big to put inside the application itself). Everything went smooth and it upgraded to unity5, but now when I run the scene, and where it starts downloading the streamed assets, I get the error:

Invalid serialized file version. File: "somefilepath". Expected version: 5.0.1f1. Actual version: 4.3.0f4

Any idea how to fix this if the assets are streamed? How can I upgrade streamed assets that are not present as files inside my unity project rather in some cloud?

I also get the following error which might also be relevant:

nvalid serialized file version. File: "mem:/CAB-076298da4d97a41348bfb20a614b6345/CAB-076298da4d97a41348bfb20a614b6345". Expected version: 5.0.1f1. Actual version: 4.3.0f41. UnityEngine.WWW:get_assetBundle()c__Iterator8:MoveNext() (at Assets/Scripts/Core/GameplayManager.cs:142)