I'm new to SML/NJ and there's some questions bothering me. I don't know how to use Math or String in the basis lib

Question

- val a= Math.sqrt 4.0; 
[autoloading]

unexpected exception (bug?) in SML/NJ: Io [Io: openIn failed on "/home/abuild/rpmbuild/BUILD/smlnj-110.99/sml.boot.amd64-unix/smlnj/basis/.cm/amd64-unix/basis.cm", No such file or directory]
  raised at: Basis/Implementation/IO/bin-io-fn.sml:626.25-626.71
             ../cm/util/safeio.sml:30.11
             ../compiler/TopLevel/interact/evalloop.sml:45.54

I tried to use Real.sqrt or just sqrt but didn't work. Do I missed something like a file or something? I wish someone would help me. My OS is opensuse leap 15.5.