Could not acquire trading lock

What this error means

AutoTrader Web shows this error when it cannot get a trading lock for the account you are using.

Before any operation — placing, modifying or cancelling an order, or reading positions, margins or orders — AutoTrader Web first takes a trading lock on that account. This makes sure that only one operation runs for any account at any moment.

The lock has two benefits:

• It keeps the account’s data consistent.
• It helps avoid the “Too many requests” error from your stock broker.

When an operation finishes, the lock is released so the next operation can take it.

Why it happens

The problem starts when your broker’s server does not answer in time. The earlier operation is still running and still holding the lock, so the next one waits its turn. If the broker has still not responded by the time that wait runs out, you get this error.

It is almost always a slow or unresponsive broker server — most often seen when a broker is under heavy load, or when their server accepts the connection but never sends a reply.

Solution

Just retry the failed operation.

The root cause is your broker’s server, which did not complete the operation in time. The real fix has to happen at the broker’s end, so retrying is the practical answer — it usually goes through once their server responds normally again.

If the message says “login lock” instead of “trading lock” — for example SD-ERR-140: Could not acquire login lock — that is the same kind of problem while logging in rather than while trading. See SD-ERR-140: Could not acquire login lock.

For related help, see What to do when one of the brokers has a problem and Request timed out error from trading platform.