Brms control statement causes sampling failure

[jsocolar]

Another user recently reported the same problem here

Sampler won't start if adapt_delta is used: why?

I’m having a super weird problem when trying to use adapt_delta in a brms model. If I run the model without adapt_delta, it converges. But if I add this parameter, I get an error message that says that there is a sampling problem: SAMPLING FOR MODEL '8905f3b5c84488b617ca68a8e8087228' NOW (CHAIN 1). [1] "Error in sampler$call_sampler(args_list[[i]]) : " [2] " VECTOR_ELT() can only be applied to a 'list', not a 'externalptr'" error occurred during calling the sampler; sampling…

I don’t know the resolution yet, but let’s move this discussion over there and hopefully we can figure it out, or somebody who already knows the answer will chime in.