In order to formally reason about distributed Erlang systems, it is necessary to have a formal semantics. In a previous paper we have proposed such a semantics for distributed Erlang. However, recent work with a model checker for Erlang revealed that the previous attempt was not good enough. In this paper we present a more accurate semantics for distributed Erlang. The more accurate semantics includes several modifications and additions to the semantics for distributed Erlang proposed by Claessen and Svensson in 2005, which in turn is an extension to Fredlund’s formal single-node semantics for Erlang. The most distinct addition to the previous semantics is the possibility to correctly model disconnected nodes.

We investigate the distributed part of the Erlang programming language, with an aim to develop robust distributed systems and algorithms running on top of Erlang runtime systems. Although the step to convert an application running on a single node to a fully distributed (multi-node) application is deceptively simple (changing calls to spawn so that processes are spawned on different nodes), there are some corner cases in the Erlang language and API where the introduction of distribution can cause problems. In this paper we discuss a number of such pitfalls, where the semantics of communicating processes differs significantly depending if the processes reside on the same node or not, we also provide some guidelines for safe programming of distributed systems.