[Solved] catkin_make error: CMake Error at CMakeLists.txt:1:

catkin_Make error:

CMake Error at CMakeLists.txt:1:
  Parse error.  Expected a command name, got unquoted argument with text
  "/opt/ros/melodic/share/catkin/cmake/toplevel.cmake".

Reason: it has been compiled once
Solution: delete cmakelists.txt in the SRC directory of the file and recompile it.

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