Why do I get xcrun error SDK "macosx10.13.4" cannot be located when using loadlibrary?

Why do I get following error when using loadlibrary on MacOS?

[~,warnings] = loadlibrary(libpath, headerpath, 'alias', 'libbf2');

Warning: Message from C preprocessor:

xcrun: error: SDK "macosx10.13.4" cannot be located

 > In loadlibrary 
 and
 >> warnings
 warnings =
     'xcrun: error: SDK "macosx10.13.4" cannot be located

      Type 'char__signed' was not found.  Defaulting to type error.

      Found on line 15 of input from line 30 of file /Library/Developer/CommandLineTools/SDKs/MacOSX10.13.sdk/usr/include/sys/_types/_int8_t.h

      Failed to parse type 'union { char *__mbstate8; long long _mbstateL ; } __mbstate_t' original input 'union { char __mbstate8 [ 128 ]; long long _mbstateL ; } __mbstate_t'
      Found on line 110 of input from line 79 of file /Library/Developer/CommandLineTools/SDKs/MacOSX10.13.sdk/usr/include/i386/_types.h

      Type '__mbstate_t' was not found.  Defaulting to type error.

      Found on line 112 of input from line 81 of file /Library/Developer/CommandLineTools/SDKs/MacOSX10.13.sdk/usr/include/i386/_types.h
      xcrun: error: SDK "macosx10.13.4" cannot be located
      '

Answer 1

[MathWorks Support Team]

The user may need to reset their active developer directory path:

Check their active developer directory path by running "xcode-select -p" in their MacOS terminal:

xcode-select -p
/Library/Developer/CommandLineTools

They can reset their active developer directory to the default command line tools path with "xcode-select -r":

sudo xcode-select -r

xcode-select -p

/Applications/Xcode.app/Contents/Developer