We recommend a new version of TWS: Version978.1g. Most important feature is to set the API message language to english. This makes it possible to keep the TWS language in your native language, but the API messages which are evaluated by our API client software in english.
When your TWS language is english, no need for this version or for changes in API settings.
If you like to have another TWS language than english, this version is recommended. How to set the API messages to english, is shown in the API settings example in german language. Just mind the orange frame.
License handles # of connected accounts more flexible
The new version detects only client accounts in use by all allocations and not all accounts associated with a connection. So you can have for instance a license for 4 accounts, when you use only 4 accounts even if your TWS / API connection manages more than 4 accounts.
This feature makes it possible to run TWS or Gateway without a noteable break or login 5 days in a row. Just setup Auto Restart feature and login once per week, e.g. at the beginning of the trading week.