TWS error 101: market-data line limit reached

Quick answer

Error 101 means the active market-data requests exceed the account’s available capacity. TWS windows and API clients can consume that capacity together. Close unused requests before adding more.

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

Step by step

1 Save the full app message first. To check a recorded TWS API log, open Help → Troubleshooting → Diagnostics → API Logs. Select its date and choose View Logs. If the list is empty, enable API logging before the next event.
2 List open watchlists, charts, scanners, and connected API apps.
3 Remove unused symbols or close unused data windows.
4 Have the API app cancel subscriptions it no longer uses instead of only hiding them.
5 Retry one needed symbol and check whether the error clears.
6 If the workload truly needs more lines, review IBKR’s current allocation rules and available options.

A practical example

You open a second chart workspace while an API app watches many symbols. A new quote now fails. Close data views you no longer need and retry one symbol. If the app keeps old requests active, closing a visible tab may not be enough. Ask it to cancel the unused feed requests. The goal is to free capacity for the quotes you actually use.

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

Screen reference

TWS View Logs dialog with View Logs, Export Logs and Export Today Logs buttons — This session has no recorded API logs in the list, so export buttons are disabled. Enable API logging before the event you need to capture. No log was exported or uploaded for this screenshot. Captured in TWS paper mode on 3 October 2026. Open the image for full size.

TWS Market Data Connections with farm purpose and status, plus API client columns — The observed services are connected and the API client list is empty. Use this panel to read current status; it does not reproduce a disconnect or prove an app handshake completed. Captured in TWS paper mode on 3 October 2026. Open the image for full size.

How to confirm the result The needed symbol should receive data while the total active workload stays within its allowance.

Mistake to avoid

A hidden app may keep its data subscriptions active. Hiding a window is not proof that requests were cancelled.

Common questions

Is this a missing exchange subscription?

No. Capacity and exchange data access are different checks.

Will a second API connection add free capacity?

Do not assume it creates a separate account allowance.

TWS error 200: contract not found or ambiguous TWS error 201: read the order rejection reason TWS error 202: why was the order cancelled? TWS delayed versus live data: how to tell How to enable TWS API logs for troubleshooting Export TWS logs for an IBKR support case

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.