Too many parallel downloads for this viewer
Short internal wording when a download concurrency lease is refused for “this viewer.” Live APIs and the /limit page more often show the account or guest strings below.
Why this happens
Same Simultaneous downloads gate (ul2_sim_dl_*) as the other parallel-limit messages. Handlers typically remap this into Too many parallel downloads for your account or the guest wait message.
Diagnose and fix
1. Treat it like any parallel-slot block: wait for a download to finish, or raise ul2_sim_dl_*.
2. See Too many parallel downloads and Parallel download limit page for the HTML wall.
3. Check nginx edge simultaneous-download if that is enabled.
4. Not a grant rate-limit or per-file download-count issue.