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Hi David, The assertion failure you are seeing means that an internal function, ncio_spx_get() in libsrc/posixio.c, is being called to read data from disk, but it's being asked to read 0 bytes. This should never happen, so it probably indicates some sort of completely unrelated problem, such as: - a bug in the calling program or in the netCDF library that is overwriting the call stack or a memory location outside of its scope - an intermittent memory error - some other hardware or software problem We have never had another report of this assertion failing, so it seems unlikely that it is a netCDF library bug. However, I won't rule out that possibility, but unless we can reproduce the problem here, we can't diagnose it or fix it. That's why we would need a small program that demonstrates the bug. Nevertheless, here are a few questions that might help narrow it down: - Have you run "make check" on the source distribution used when your netCDF library was installed, and did it report any problems? - What version of netCDF are you linking against? - What platform (computer and operating system) are you using? - Do you run other programs on this platform that occasionally fail in mysterious ways :-) ? If so, have you run memory test software? It might also help to look at the posixio.c file in libsrc and use a debugger to see what parameters ncio_spx_get() is being called with when the assertion violation occurs. That function is only explicitly called in one place, but it may be called elsewhere through a function pointer and using a debugger on the core file resulting from the assertion violation might reveal a way we don't know about that the function could be called with 0 for the extent. --Russ Russ Rew UCAR Unidata Program address@hidden http://www.unidata.ucar.edu Ticket Details =================== Ticket ID: JZT-264094 Department: Support netCDF Priority: Critical Status: Closed