I am using try. I have found that sometimes errors are not caught by try. For example, I got the following error message from code that was wrapped in try. After the error, my R CMD BATCH aborted. Error in assign(".target", method at target, envir = envir) : no function to return from, jumping to top level Calls: reverseComplement -> loadMethod -> loadMethod -> assign Execution halted This specific error is in relation to the emails posted by Herve about problems with the methods package (I think), and it also happens inside a large piece of code that takes several hours to execute. So it is not easy to give a reproducible example. I am however surprised by the fact that try does not catch all errors - are there different error levels in R? Kasper