TWS connects but orders fail: check Read-Only API

Quick answer

Read-Only API can allow an app to connect while blocking its trading requests. Find the setting under API → Settings. Clear it only for an app you intend to allow to trade, then check for any separate rejection.

Educational software guidance. Trading involves risk. Read the financial and information disclaimers.

Step by step

1 Open Global Configuration → API → Settings in the same TWS session used by the app.
2 Locate Read-Only API near the top. Note whether it is checked.
3 If you only need data, leave it checked. If you intend to allow order request, use a paper session first and clear the box.
4 Click Apply and OK. Reconnect the app if it still reports the old state.
5 Read the next result carefully. A permission, contract, or margin error is a different problem and needs its own fix.

A practical example

An app may show your account and still say that it cannot send an order. That can be the expected result with read-only access. If you only want to view data, there is no fault to fix. If you want the app to trade, first use the paper account and check the read-only box. Change it only for that planned use. Then read any new broker response as a new clue.

Illustrative scenario, not a record of a trade placed during this review.

Screen reference

Start in Mosaic with File → Global Configuration. Then choose the panel named in the steps.

TWS API Settings showing socket clients, read-only access, port and logging — Find the named control in API → Settings. The displayed values belong to a paper session and are examples, not universal recommendations. Captured in TWS paper mode on 3 October 2026. Open the image for full size.

How to confirm the result The app should no longer report that the API is read-only. This check does not establish that an order was filled.

Mistake to avoid

Do not disable every precaution to solve this one setting. Read-only access and individual order warnings serve different purposes.

Common questions

Can I leave read-only on for monitoring?

Yes, where your monitoring app supports that mode.

Does a green connection mean trading is enabled?

No. Connectivity and permission to submit orders are separate checks.

How to enable the TWS API for PickMyTrade TWS error 502: cannot connect to the API TWS and IB Gateway ports: paper versus live TWS error 507 or EOF: the API socket closed

Financial and information disclaimers

Financial disclaimer

These guides explain software. They are for education, not financial, investment, tax, or legal advice. No example is a suggestion to buy or sell a product or use a trading strategy. Trading can lose money, including all funds you put at risk. With margin, futures, short sales, or some options, losses can exceed your starting funds. Automation can fail, send duplicate orders, or act late. Stops do not guarantee a fill or a price. Review your orders and positions, and seek advice from a qualified professional for your own needs. Paper trades, examples, and past results do not predict live results or promise a profit.

Information disclaimer

This is general help based on the sources and check date shown on the page. Screens, settings, fees, data access, and product support can change or differ by app version, account, country, and broker. The content may contain errors or become out of date; accuracy, completeness, and continuous service are not guaranteed. Check current broker and app instructions before acting. Screenshots show where controls are; they do not prove that an order test passed. This guide does not replace broker terms or risk notices. References to IBKR and TradingView identify their products and do not imply their endorsement of this guide.