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Eclipse launch error: cannot connect to VM / timeout

Eclipse IDE, Java

Application launch fails with 'Could not connect to the virtual machine' or a timeout.

What it means (root cause)

Port conflict, corrupt launch configuration, or a JRE mismatch between workspace and launched app.

The symptom developers actually see: Application launch fails with 'Could not connect to the virtual machine' or a timeout.

How to avoid it: Keep a single consistent JDK across the IDE and runtimes.

Step-by-step fix

Concrete, ordered steps from the dataset. Apply them in order; each line is a verified action, not generic advice.

  1. 1Delete and recreate the launch configuration (Run > Run Configurations).
  2. 2Free the debug port or pick a different one in the configuration.
  3. 3Match the project JRE to the installed JDK under Installed JREs.

Where this error appears

Languages, frameworks, and runtimes where this error is observed (from the 2026 DevFixPro error dataset, retrieved 2026-08-29):

Eclipse IDEJava

Eclipse IDE on any OS running a JVM app. It is an IDE/launch-config issue, not a problem in your source.

How to prevent it & common questions

Practical prevention plus the questions developers ask most about this error.

What does "Eclipse launch error: cannot connect to VM / timeout" mean?

Port conflict, corrupt launch configuration, or a JRE mismatch between workspace and launched app.

Which environments are affected by Eclipse launch error: cannot connect to VM / timeout?

Eclipse IDE, Java

How do I fix Eclipse launch error: cannot connect to VM / timeout?

Delete and recreate the launch configuration (Run > Run Configurations). Free the debug port or pick a different one in the configuration. Match the project JRE to the installed JDK under Installed JREs.

How do I prevent Eclipse launch error: cannot connect to VM / timeout?

Keep a single consistent JDK across the IDE and runtimes.

Related DevFixPro tools

Real, browser-only utilities on DevFixPro that help while you work through this issue. These are navigation aids, not a substitute for the fix above.

CFG

YAML / INI Config Linter

Catch tabs, trailing spaces, and malformed key/value lines in config files.

Open tool →
● Data updated 2026-08-29

Sources & attribution

  • Error records aggregated from Google Search Console query gaps (2026-05-21~2026-08-18) for devfixpro.com, plus official framework docs (MDN, Node.js docs, Python docs, Go.dev, Rust book, Oracle Java docs, Docker docs, npm docs). Source dataset retrieved 2026-08-29. License: CC BY 4.0 — attribute DevFixPro (devfixpro.com).
  • Official reference: https://www.eclipse.org/eclipse/docs/
  • All cause, environment, fix and prevention text on this page is taken verbatim from the DevFixPro 2026 error dataset. DevFixPro does not invent root causes or fixes.
How this Eclipse launch error: cannot connect to VM / timeout page is built

Each error page is generated from a single record in the DevFixPro 2026 error dataset. The meaning, root cause, environments, fix steps, prevention, and official references are copied verbatim from that dataset and its official-doc sources; related-error links are computed from the error's category and explicit peer list. No root cause or fix is invented. The retrieval date for this dataset is 2026-08-29.

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