If clearing the cache failed, the app files themselves may be corrupted. Remove the application entirely.
Clear cache / reset settings
Most v461 errors are caused by "ghost" data stuck in the application’s temporary memory.
Ucast periodically updates its RTMP stack. If you are running firmware older than Q8_V2.1.6 (example), the handshake protocol may be incompatible with newer CDNs like Fastly or Cloudfront.
Some CDNs (like Akamai) use non-standard ports. By default, Ucast uses Port 1935.