In order to not trigger a compilation cascade, gfortran only overwrites a .mod file when its MD5 sum has changed.
Seemingly, the mod-file versioning has the side effect that the MOD file is not overwritten if there are no other changes but the version number, which causes the version-mismatch error. I'm not sure whether this is a problem between 4.x and 4.(x+1) versions as the .mod file probably has changed in an incompatible way (different MD5 sum), but still it is annoying. Expected: If the version number does not match, the file is written nevertheless. (Maybe the error also occurs at a different place, I have not yet checked the source code.) -- Summary: [4.4 Regression] .mod file versioning causes error instead of overwritting the file Product: gcc Version: 4.4.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: fortran AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: burnus at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39309