Untiy 3.4 can't load the AssetBundle created by Unity 3.3

I have many AssetBundles which are created in Unity 3.3. Everything works fine.

After I upgrade to Unity 3.4 and generate the application, it will crash when loading these AssetBundles. I can see the error messages shown in Organizer. It says something like “can’t load the specified file …”

Does this mean that, I have to re-generate all AssetBunldes using Unity 3.4. That’s a huge workload. The new version should load the old version, right?

AssetBundles on iOS need to be rebuilt with new versions of Unity.

In the web player we avoid this limitations, but on mobile we are using a technique that reduces distribution size and loading time but instead your asset bundles have to be built with the right version of Unity.

Generally it’s a good idea to have a work flow where you can automatically regenerate all asset bundles at any point from your project folder.

Thanks!