Such errors will be displayed if JDownloader recognizes a blocked connection.
This is nothing that JDownloader can prohibit so you need to take measures yourself to get rid of such problems.
| Problem type | Examples | Solutions | 
|---|---|---|
| Internet security provider | Cloudflare, DDoS-Guard, ShieldSquare | Read this FAQ | 
| DNS blocks issued by governments or private companies | Change your DNS server -> Instructions | |
| Local firewall applications | Bitdefender, NOD32, Eset Internet Security | Configure your firewall properly | 
| Network-wide security applications commonly used in | WireFilter, Zscaler, Sucuri.net | Use a VPN | 
If you are trying to download from a (video) streaming website, this download method might help to get around "Blocked by ..." errors.