Error 529 usually appears when Roblox cannot complete a service request. It can happen during an outage or a period of heavy traffic, although the number alone does not prove that every Roblox service is down.
Before changing passwords or reinstalling the app, check whether other players are seeing the same problem.
Check the official status page
Open status.roblox.com and look for an active incident. The page separates services such as games, the website, Marketplace and Studio, so one part may fail while another still works.
An incident can also begin before the status page is updated. If several devices and games fail at once, wait a few minutes and check again.
Try again without spamming
Close Roblox and wait briefly before reopening it. Sending the same request over and over does not make a busy service recover faster.
You can restart your device and check the connection, but avoid changing lots of settings during a confirmed Roblox outage. Those changes will not repair Roblox's servers.
When only you see it
Try another network if a parent says it is safe to do so, or ask whether a firewall or content filter is blocking Roblox. Make sure the app is updated from the official store.
If the error continues after Roblox reports normal service, note the time, device and game, then contact Roblox Support. That information is more useful than saying only that Roblox is broken.