HTTP Error 503

I’m getting some strange fails… among successes (before I only ever got all-fails, apparently due to usage of dl instead of dlp, so this must be for another reason)… and that is the error message I get… could it, possibly, be because it’s trying to import too many too quickly? I notice at one point it seems to get up to 40% too, but then still fails…

And, actually, it also begins with « Command failed with exit code 1 »… I notice some fails with just that too, no 503 in sight, so, not sure what’s causing this… is it inevitable when syncing channels with lots of videos?