What causes "esbuild exited before the rebuild completed" in denoland/deno?

Re-run the bundle — the next start respawns the esbuild service cleanly

esbuild exited before the rebuild completed

Error message

esbuild exited before the rebuild completed

What it means

In `deno bundle --watch`, after sending a rebuild request Deno waits on esbuild's rebuild-complete event over a channel. If that channel closes instead of yielding a response, the esbuild child process exited (crashed or was killed) before finishing the rebuild, and watch mode surfaces this error.

Solutions

Re-run the bundle — the next start respawns the esbuild service cleanly
Check `dmesg`/journalctl for an OOM kill of esbuild; free memory or split the bundle to reduce peak usage
Update deno (bundled esbuild fixes land often); if esbuild panicked, capture its stderr and report the repro

Defensive patterns

Strategy: retry

Try / catch

In watch/build scripts, catch this error, treat the esbuild service as dead, and restart the bundling task (bounded retries with backoff) rather than propagating immediately.

Prevention

Give dev machines and CI enough memory for large incremental rebuilds
Avoid killing esbuild children with blanket cleanup scripts
Update deno regularly to pick up bundled esbuild fixes

When it happens

Trigger: A watch-mode rebuild during which the esbuild service dies: OOM kill, manual kill of the esbuild process, an esbuild panic on pathological input, or system shutdown mid-rebuild.

Common situations: Memory-constrained dev machines or CI where esbuild gets OOM-killed on large rebuilds; stray process cleanup scripts killing esbuild children.

Related errors

AI-assisted analysis of denoland/deno@9ad36f7a2c (2026-08-20). Data as JSON: /api/errors/fba65545d4173b5b. Report an issue: GitHub.

Appendix: source

Thrown at cli/tools/bundle/mod.rs:1185

    Ok(response)
  }

  async fn rebuild(&mut self) -> Result<BuildResponse, AnyError> {
    match self.mode {
      BundlingMode::OneShot => {
        panic!("rebuild not supported for one-shot mode")
      }
      BundlingMode::Watch => {
        log::trace!("sending rebuild request");
        let _response = self
          .client
          .send_rebuild_request(0)
          .await
          .context("failed to send rebuild request to esbuild")?
          .map_err(|e| message_to_error(&e, &self.cwd))?;
        let response = self.on_end_rx.recv().await.ok_or_else(|| {
          deno_core::anyhow::anyhow!(
            "esbuild exited before the rebuild completed"
          )
        })?;
        Ok(response.into())
      }
    }
  }

  async fn reload_specifiers(
    &mut self,
    changed_paths: &[PathBuf],
  ) -> Result<(), AnyError> {
    self.reload_html_entrypoints(changed_paths)?;
    self.plugin_handler.reload_specifiers(changed_paths).await?;
    Ok(())
  }

  fn reload_html_entrypoints(

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