Troubleshooting

Most Arc snags come down to a handful of causes. Here they are. If the slice uses the Chronicle integration, see Chronicle troubleshooting for event-store-specific issues.

My frontend can’t find the generated proxy

Proxies are generated when the backend builds. If the import doesn’t resolve:

Run dotnet build on the backend and confirm it succeeds — no proxies are emitted until the C# compiles.
Check the command/query is discoverable: a [Command] record with a Handle() method, or a static query method on a [ReadModel].
Make sure proxy generation is targeting the right output folder for your frontend (see Proxy Generation).

I changed the C# but the TypeScript is stale

The proxies regenerate on build. Rebuild the backend; the frontend types update with it. If a renamed property doesn’t surface, you’ve found the feature working — the old name should now fail to compile until you update the call site.

My command’s OK/Submit button stays disabled

The command isn’t considered valid. The usual cause: a required value is being set in onBeforeExecute instead of initialValues. onBeforeExecute runs at execution time — too late to affect validity — so the form never becomes valid. Put injected required values (like a parent id) in initialValues; reserve onBeforeExecute for generated values that don’t gate validity (like a new Guid). See Building a form.

My command returns 401 or 403

That’s authorization. Check that:

the caller is authenticated, and
the caller has the role the command requires ([Roles(...)] on the command — or on the query method for a 403 on reads).

For local development you can generate a principal so you can exercise authorized endpoints without a full login — see Identity and Authorizing commands and queries.

My validation isn’t firing

Arc discovers a CommandValidator<TCommand> by convention. Confirm the validator’s generic type matches the command exactly, and that any async rule that needs a dependency takes it via the validator’s constructor. See Commands.

My query returns nothing

This is usually the read side, not proxy generation:

Confirm the command wrote the document or entity you expect.
Check any query predicate, especially ids passed through [Key].
If the query is observable, confirm the underlying store is configured for observation: MongoDB change streams or EF observed DbSets.

If the slice is backed by Chronicle, also check that the projection has caught up and maps the events you appended.