BoundaryML/baml · error

Failed to update runtime after reloading files

Error message

Failed to update runtime after reloading files: {e}

What it means

After reload reloads files, it rebuilds each project's runtime; a failure updating the runtime (e.g. errors compiling the BAML schema into a runtime) is logged via tracing::error! and surfaced as 'Failed to update runtime after reloading files'. It indicates the reloaded sources are inconsistent or invalid for runtime construction.

Solutions

1. Read the inner error to find the offending BAML file/diagnostic
2. Fix the BAML syntax/type errors in the reloaded sources
3. Check baml_settings.feature_flags match the current schema version
4. Retry the reload (or restart the server) once sources are valid

Example fix

// before: broken baml on disk
function Foo { prompt #"..." } // malformed
// after: valid definition
function Foo() -> string { client GPT4o prompt #"hi" }

// validate baml files compile (e.g. via CLI) before reload
$ baml-cli validate ./baml_src

try { await triggerReload(); } catch (e) { if (String(e).includes('update runtime')) { showDiagnostics(e.cause); /* fix sources, then */ await triggerReload(); } else throw e; }

When it happens

Trigger: load_files succeeded but update_runtime fails: BAML source with syntax/type errors introduced on disk, inconsistent partial file states mid-reload, or feature-flag configuration incompatible with the new sources.

Common situations: Saving a broken .baml file while the LSP watches the directory; git branch switch leaving transiently invalid sources; feature_flags in settings that no longer match the reloaded schema.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• Could not update runtime
• Failed to load project files
• {0}
• {0}
• -32803

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/e1705cdbff4ab468. Report an issue: GitHub.

Appendix: source

Thrown at engine/language_server/src/session.rs:273

                tracing::info!(
                    "Loaded {} files for project root: {:?}",
                    files_map.len(),
                    project_root
                );

                {
                    let default_flags = vec!["beta".to_string()];
                    project.lock().update_runtime(
                        notifier.clone(),
                        self.baml_settings
                            .feature_flags
                            .as_ref()
                            .unwrap_or(&default_flags),
                    )
                }
                .map_err(|e| {
                    tracing::error!("Failed to update runtime after reloading files: {e}");
                    anyhow::anyhow!("Failed to update runtime after reloading files: {e}")
                })?;
                Ok(files_map)
            })
            .collect::<anyhow::Result<Vec<_>>>()?;

        let total_files: usize = project_updates.iter().map(|m| m.len()).sum();
        tracing::info!(
            "Initial reload complete: {} projects, {} total files",
            project_updates.len(),
            total_files
        );

        // Guard no longer used. We can drop now instead of waiting for the end
        // of scope.
        drop(baml_src_projects);

        let files: Vec<(DocumentKey, String)> = project_updates
            .into_iter()

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