Hello, my model suddenly stopped working, with following error message:

C:/OpenModelica1.12.0-64bit//share/omc/scripts/Compile.bat 1D gcc mingw64 parallel 1 0
PATH = "C:\OpenModelica1.12.0-64bit\tools\msys\mingw64\bin;C:\OpenModelica1.12.0-64bit\tools\msys\mingw64\bin\..\..\usr\bin;"
gcc    -falign-functions -msse2 -mfpmath=sse      -I"C:/OpenModelica1.12.0-64bit//include/omc/c" -I. -DOPENMODELICA_XML_FROM_FILE_AT_RUNTIME -DOMC_MODEL_PREFIX=1D -DOMC_NUM_MIXED_SYSTEMS=0 -DOMC_NUM_LINEAR_SYSTEMS=19 -DOMC_NUM_NONLINEAR_SYSTEMS=5 -DOMC_NDELAY_EXPRESSIONS=0 -DOMC_NVAR_STRING=0  -c -o 1D.o 1D.c
In file included from 1D.c:2:0:
1D_model.h:2:14: error: operator "defined" requires an identifier
#if !defined(1D__MODEL_H)
              ^

other models are running fine. The error is right at the start of the compiling progress,

What is wrong here?

Best regards