Bloom and Blur PostEffects don't work after updating to Unity 5.6.0f3

After updating Unity to 5.6.0f3 the Bloom and Blur PostEffects throw this error:> NullReferenceException: Object reference not set to an instance of an object> UnityStandardAssets.ImageEffects.Bloom.OnRenderImage (UnityEngine.RenderTexture source, UnityEngine.RenderTexture destination) (at Assets/Standard Assets/Effects/ImageEffects/Scripts/Bloom.cs:121) The method is OnRenderImage and its trying to access a property of the RenderTexture source (the first argument), but source is null. And the screen is black, obviously. All post-effects receive a null as the source. Any ideas?