Argument 'autocor' should be specified within the 'formula' argument

I’m running a mixed-effects model with two (maybe three) random variables so at the end of running my model I get a warning:
Argument ‘autocor’ should be specified within the ‘formula’ argument. See ?brmsformula for help.

I read the help page but I really don’t know how to choose the autocor type.
My response variable is a binary factor and the independent variables contain mostly binary factors and continuous variables.

So my question is how do I choose the specification of “autocor”?

Hi, sorry for not answering earlier. Could you share the full code you use to invoke brms, and also (a subset) of the data, if possible?

Also what is the exact version of brms you are using?

See ?brms::arma for examples how to use autocor terms now.