# Communication (parallel processing) problem

**URL:** <https://gromacs.bioexcel.eu/t/communication-parallel-processing-problem/1403>\
**Category:** User discussions\
**Created:** [January 8, 2021, 9:40am UTC](https://gromacs.bioexcel.eu/t/communication-parallel-processing-problem/1403 "2021-01-08T09:40:13Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![btam125](https://avatars.discourse-cdn.com/v4/letter/b/a88e57/32.png) [@btam125](https://gromacs.bioexcel.eu/u/btam125)\
**Post date:** [January 8, 2021, 9:40am UTC](https://gromacs.bioexcel.eu/t/communication-parallel-processing-problem/1403/1 "2021-01-08T09:40:13Z")

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GROMACS version: 2020  
GROMACS modification: No  
Here post your question

Dear Gromacs user,

This problem kept reoccurring when I restart my simulation, this happened many times and I have to restart the simulation everytime. Can someone give me some clue what is happening with this error? This never occurred with older version of Gromacs.

rogram: gmx mdrun, version 2020-UNCHECKED  
Function: std::tuple\<gmx::StartingBehavior, std::unique\_ptr\<t\_fileio, gmx::functor\_wrapper\<t\_fileio, gmx::closeLogFile\> \> \> gmx::handleRestart(bool, MPI\_Comm, const gmx\_multisim\_t\*, gmx::AppendingBehavior, int, t\_filenm\*)  
MPI rank: 27 (out of 40)

Communication (parallel processing) problem:  
Source file: src/gromacs/mdrunutility/handlerestart.cpp (line 681)  
Function: std::tuple\<gmx::StartingBehavior, std::unique\_ptr\<t\_fileio, gmx::functor\_wrapper\<t\_fileio, gmx::closeLogFile\> \> \> gmx::handleRestart(bool, MPI\_Comm, const gmx\_multisim\_t\*, gmx::AppendingBehavior, int, t\_filenm\*)  
MPI rank: 38 (out of 40)

Communication (parallel processing) problem:  
Another MPI rank encountered an exception

## For more information and tips for troubleshooting, please check the GROMACS website at [Errors - Gromacs](http://www.gromacs.org/Documentation/Errors)

Another MPI rank encountered an exception

For more information and tips for troubleshooting, please check the GROMACS  
website at [Errors - Gromacs](http://www.gromacs.org/Documentation/Errors)

Thanks a lot!

Best,

Ben