What does this error mean?

A throwable error of some type was caught when executing a BinLog thread.

Why does this error occur?

This is a catch-all error message. Any throwable error could trigger this. There is not a specific cause that can be called out.

How do you fix this error?

Please look at any available stack trace associated with this error to determine a root cause in order to plan a fix for it. If needed, Datastax Support can help.