Hello,
I do not see what the error is in your listing, so it is difficult to say, I would just suspect some mismatch between simple and double precision SERAFIN format files. Otherwise I would need the files of the case that crashes to see what happens.
Anyway this restart mode is not mandatory, you can also remove it and use simple continuations (COMPUTATION CONTINUED = YES and PREVIOUS COMPUTATION FILE=..., also in double precision if you want).
The restart mode is to get continuations without any difference in digits (compared to a longer run without restart), it was asked by researchers that work on data assimilation and in that case even the initial guess for solvers must be stored in theory, and all the operations must be done in the same order, we have to store the depth, because retrieving it from the mesh creates truncation errors, etc.).
With best regards,
Jean-Michel Hervouet