IntelliJ plugin repository unreachable behind proxy: DNS failure or TLS certificate validation error

IntelliJ plugin repository unreachable behind proxy: DNS failure or TLS certificate validation error

The goal is to determine why IntelliJ IDEA cannot reach the plugin repository when operating behind a corporate proxy. The Plugins dialog returns a generic connection failure, and the proxy connection test only confirms basic reachability, not a successful TLS handshake to the repository endpoint.

IntelliJ validates repository traffic through the JetBrains Runtime trust store and the IDE’s Server Certificates manager rather than automatically using the operating system store. DNS lookup failures and certificate validation failures can produce the same surface error, and behavior may differ between the bundled runtime and a custom JDK. Importing a proxy root CA may be version-sensitive, and background update checks can cache validation results differently from foreground plugin searches.

Which log entry distinguishes a DNS resolution failure from a TLS certificate validation failure for plugin repository traffic? Does trusting the proxy certificate in the IDE’s Server Certificates manager also require updating the JDK trust store for the bundled JetBrains Runtime? Can background plugin update checks and foreground repository searches maintain separate certificate trust states?