denoland/deno · error

`deno {}` is not supported when configuration file contains

Error message

`deno {}` is not supported when configuration file contains an "importMap" field. Inline the import map into the Deno configuration file.
    at {}

What it means

Dependency-mutating commands (`deno add`/`remove`, via cmd_name) refuse to run when the active deno.json still uses the legacy top-level `"importMap"` field. The config updater rewrites deno.json, and external import map files cannot be edited safely, so Deno asks you to inline the map first.

Source

Thrown at cli/tools/pm/mod.rs:553

pub async fn add(
  flags: Arc<Flags>,
  add_flags: AddFlags,
  cmd_name: AddCommandName,
) -> Result<(), AnyError> {
  let save_exact = add_flags.save_exact;
  let (cli_factory, force_package_json, mut npm_config, mut deno_config) =
    load_configs(
      &flags,
      || add_flags.packages.iter().any(|s| s.starts_with("jsr:")),
      add_flags.package_json,
      true,
    )?;

  if let Some(deno) = &deno_config
    && deno.obj().get("importMap").is_some()
  {
    bail!(
      concat!(
        "`deno {}` is not supported when configuration file contains an \"importMap\" field. ",
        "Inline the import map into the Deno configuration file.\n",
        "    at {}",
      ),
      cmd_name,
      deno.display_path(),
    );
  }

  let start_dir = cli_factory.cli_options()?.start_dir.dir_path();

  // only prefer to add npm deps to `package.json` if there isn't a closer deno.json.
  // example: if deno.json is in the CWD and package.json is in the parent, we should add
  // npm deps to deno.json, since it's closer
  let prefer_npm_config = match (npm_config.as_ref(), deno_config.as_ref()) {
    (Some(npm), Some(deno)) => {
      let npm_distance = path_distance(&npm.path, &start_dir);

View on GitHub (pinned to 9ad36f7a2c)

Solutions

1. Move the map contents into deno.json under `"imports"` and delete the `importMap` field, then re-run the command.
2. Keep `scopes` too if your map used them: `{ "imports": {...}, "scopes": {...} }`.
3. Remove the now-unused import.map.json file to avoid confusion.

Example fix

// deno.json (before)
{ "importMap": "./import.map.json" }
// import.map.json
{ "imports": { "foo": "https://example.com/foo/mod.ts" } }
// deno.json (after)
{
  "imports": { "foo": "https://example.com/foo/mod.ts" }
}

const cfg = JSON.parse(readFileSync("deno.json", "utf8"));
if ("importMap" in cfg) {
  console.error("deno.json uses legacy top-level 'importMap'; inline it as 'imports' first");
  process.exit(1);
}

const usesLegacyImportMap = (cfg: Record<string, unknown>): boolean =>
  "importMap" in cfg;

When it happens

Trigger: deno.json contains `"importMap": "./import.map.json"` (top-level field) and you run `deno add ...` or `deno remove ...`. The check reads the `importMap` key on the loaded config object.

Common situations: Older projects predating inline `imports`; migration leftovers; import map maintained as a separate file shared across tools.

Related errors

• Unsupported 'certFile' / 'keyFile' options provided: use 'ce
• Could not get parent of {} ({})
• No rules have been configured
• remote deno.json files are not supported
• A deno.json file could not be found or created

AI-assisted analysis of denoland/deno@9ad36f7a2c (2026-08-20). Data as JSON: /api/errors/5b8f096c907213d6. Report an issue: GitHub.