As noted in this thread the mfix-solver package in the 26.1 release may have GLIBC compatibility issues on older systems. If you see any messages regarding GLIBC_2.35 please reinstall. Note that this is not a new release since it’s built from the same codebase, it’s just a new package build that has the same 26.1 version number:
# Name Version Build Channel
mfix-solver 26.1 h94061f0_1 https://mfix.netl.doe.gov
the build string is incremented from _0 to _1