Ran into this twice... While installing an Arena update, only in the end i am reminded of closing Adobe programs. This results in the DXV Exporters not intsalling right. AE will say on startup that somethings not right with the DXV3 exporter. Only way to fix ist to reinstall Arena.
Wouldnt it make sense to check for open Adobe Programs on Arena update start, rather than running into that problem towards the end, resulting in re-installion?