nfortunately no apart that forme it means you have a complex model ;)
But it looks like there is un undefined variable, so are you sure your BC are real everywhere or over the time ?
For the second it's eitherthe solver is stuck typically on a steep edge of some change, or it does not have enough steps to converge, and you should increase the maximum allowed steps
Try to split your problem, or solve just one physics to check that it is fully possible to fiond a solution in a simpler case