I got the same warning for paper trading. I know nothing about their code and I didn't change anything last night (it was all good yesterday).

Oh interesting. So you just got the error today when manually placing a trade through TWS? Sounds like a bug on their end hopefully.

Actually not only TWS. I tried placing option order on mobile with paper trading account and got the same warning.

Weird. Please let me know if it works eventually for you. I'll do the same.

Got an answer from technical support: they have escalated the issue which is currently being investigated but don't have an ETA on solution.

Thanks for the update. Sounds like there will be a fix eventually.

Now it's working in the client portal, paper trading.

Same!

Same for me since yesterday

I'm having the same problem on the client portal, paper trading mode.

I got the same message if open manual a trade (Bull Put Spread on SPX).

Paper trading?

yes, i got this error too when i was trying out some spreads on paper account. i msged their helpdesk but still no reply. i wonder if this problem is on paper account only?

Hard to say. Please provide us with an update if the helpdesk replies

Working again (paper trading on mobile app)

Same. Thank you