: Go to Window > Preferences > General > Network Connections . Change the Active Provider from Manual to Native (to use your OS settings) or Direct .
Eclipse caches repository metadata, and if that cache becomes corrupted, it will fail to read the repository even if the URL is correct. Close Eclipse. : Go to Window > Preferences > General > Network Connections
Locate the entry for Luna (usually http://download.eclipse.org/releases/luna/ ). Select it and click . Change the prefix from http:// to https:// . Close Eclipse
The most common cause for this error in modern environments is the shift from http to https . Older Eclipse versions like Luna were often pre-configured with http links, which many servers now redirect or block. Change the prefix from http:// to https://
Alternatively, try adding a trailing slash ( / ) to the end of the URL if it is missing. 2. Fix SSL and Certificate Issues