h2o.init报错301 Moved Permanently，OSX+R环境求排查方向

Hey there, sorry to hear you’re hitting this frustrating 301 error when firing up H2O. Let’s walk through some targeted checks and fixes tailored to your specific setup:

• Verify H2O-R Version Compatibility
  R 3.4.3 is an older release, and newer H2O versions often drop support for legacy R builds. First, check your installed H2O version with:

  packageVersion("h2o")
  

  Cross-reference this with H2O’s release notes to confirm it’s compatible with R 3.4.3. If not, uninstall the current package (remove.packages("h2o")) and install a compatible archived version (look for releases from around 2018-2019, as those typically support R 3.4.x).

• Force Local IP/Port to Avoid Redirects
  H2O sometimes tries to resolve default hostnames that might trigger unexpected redirects. Override this by explicitly specifying a local loopback address and unused port:

  h2o.init(ip = "127.0.0.1", port = 54321, startH2O = TRUE)
  

  Before running this, make sure the port isn’t in use—on OS X, run this in Terminal to check:

  lsof -i :54321
  

  If a process is using it, pick another port (like 54322) and try again.

• Kill Stale H2O Processes & Clear Cache
  Leftover Java-based H2O processes (since H2O runs on Java) can cause weird connection issues. Open Activity Monitor, search for "java", and quit any H2O-related processes. Then delete H2O’s local cache directory:

  rm -rf ~/.h2o
  

  Now try initializing H2O again fresh.

• Disable System/Proxy Interference
  OS X 10.12.6’s proxy settings might be redirecting H2O’s local requests. Go to System Preferences > Network > Advanced > Proxy and ensure no unnecessary proxies are enabled. If you do use a proxy, add 127.0.0.1 to the "Bypass proxy settings for these Hosts & Domains" list.

  Also check R’s proxy environment variables—run these to see if they’re set:

  Sys.getenv(c("http_proxy", "https_proxy"))
  

  If either returns a value, unset them temporarily before initializing H2O:

  Sys.unsetenv("http_proxy")
  Sys.unsetenv("https_proxy")
  h2o.init()
  

• Explicitly Target Local H2O URL
  Tell H2O exactly where to connect to avoid any automatic redirection logic:

  h2o.init(url = "http://127.0.0.1:54321", startH2O = TRUE)
  

  This forces the connection to your local instance directly, skipping any hostname resolution that might be causing the 301.

If none of these steps resolve the issue, run h2o.init(verbose = TRUE) and share the full output—this will give more clues about where the redirect is coming from.

内容的提问来源于stack exchange，提问作者zkurtz