Hello Nico, The problem is probably not related to "MPI_SEND not found". The CMake file is trying first to find if there is a build-in mpi in the compiler. Since, it did not find one, it is looking for a MPI library, which it found at the path indicated in the screenshot that you sent us. Cheers, Jacques ________________________________ From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of Nico Clinco <nicoclinco@gmail.com> Sent: Thursday, February 8, 2024 2:37 PM To: ankanggao@ustc.edu.cn <ankanggao@ustc.edu.cn> Cc: nektar-users@imperial.ac.uk <nektar-users@imperial.ac.uk> Subject: Re: [Nektar-users] Issues with compilation You don't often get email from nicoclinco@gmail.com. Learn why this is important<https://aka.ms/LearnAboutSenderIdentification> This email from nicoclinco@gmail.com originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list<https://spam.ic.ac.uk/SpamConsole/Senders.aspx> to disable email stamping for this address. Hello, i have tried also defining CC=mpiCC and CCX=mpiCXX but nothing, the same problem. I want to add that i am using the following modules: gnu9/9.4.0 cmake/3.24.2 openmpi4 Thanks in advance, Nicola