zed-industries/zed · error

Could not resolve task variables within a debug scenario

Error message

Could not resolve task variables within a debug scenario

What it means

A debug scenario's `build` entry is resolved from a task template: `task_template.resolve_task("debug-build-task", &task_context)` substitutes template variables against the task context; if any variable cannot be resolved it returns None and the debug session aborts with this error (running.rs:1143). The error is about variable substitution inside the build task, not about the debug config itself.

Source

Thrown at crates/debugger_ui/src/session/running.rs:1143

                        let task = task_store.update(cx, |this, cx| {
                            this.task_inventory().map(|inventory| {
                                inventory.read(cx).task_template_by_label(
                                    buffer,
                                    worktree_id,
                                    label,
                                    cx,
                                )
                            })
                        })?;
                        let task = match task {
                            Some(task) => task.await,
                            None => None,
                        }.with_context(|| format!("Couldn't find task template for {build:?}"))?;
                        (task, None)
                    }
                };
                let Some(mut task) = task_template.resolve_task("debug-build-task", &task_context) else {
                    anyhow::bail!("Could not resolve task variables within a debug scenario");
                };

                let locator_name = if let Some(locator_name) = locator_name {
                    extra_config = config.clone();
                    debug_assert!(!config_is_valid);
                    Some(locator_name)
                } else if !config_is_valid {
                    let task = dap_store
                        .update(cx, |this, cx| {
                            this.debug_scenario_for_build_task(
                                task.original_task().clone(),
                                adapter.clone().into(),
                                task.display_label().to_owned().into(),
                                cx,
                            )

                        });
                    if let Ok(t) = task {

View on GitHub (pinned to f4178619ac)

Solutions

1. Open the referenced build task template and replace unsupported variables with concrete values or supported ones ($ZED_WORKTREE_ROOT, $ZED_FILE, $ZED_ROW).
2. Run the same task standalone (task runner) to see which variable fails to substitute — the task UI shows the unresolved template.
3. Start the debug session from a context that provides the needed values (open the target file in the right worktree) before invoking the scenario.

Example fix

// before (build task template — unresolvable in debug context)
[
  { "label": "build", "command": "make build TARGET=$MY_CUSTOM_VAR", "use_new_terminal": true }
]

// after
[
  { "label": "build", "command": "make build", "cwd": "$ZED_WORKTREE_ROOT", "use_new_terminal": true }
]

// dry-run variable resolution before launching the debug session
let resolved = task_template.resolve_task("debug-build-task", &task_context);
if resolved.is_none() {
    return Err(anyhow!("build task template has variables the current context cannot resolve"));
}

On failure, fall back to showing the raw template with unresolvable variables highlighted (run the same task standalone in the task runner) instead of a bare bail.

When it happens

Trigger: A build task template referencing variables the debug task context does not provide — file-relative variables when no file context exists, custom/user variables, or a variable name that is not defined; also when the resolved context (worktree, active item) differs from what the template assumes.

Common situations: Running a debug scenario from a context with no open file; templates copied from tasks.json that use program-specific variables; variable renames after a Zed update; multi-worktree setups where the template assumes the wrong worktree root.

Related errors

• Cannot have two different hosts in debug configuration
• Cannot have two different ports in debug configuration
• debug config not found in mode: {mode}
• No process selected with config that contains {}
• Build failed

AI-assisted analysis of zed-industries/zed@f4178619ac (2026-08-20). Data as JSON: /api/errors/15a742145d902832. Report an issue: GitHub.