Fixing X11 Error on macOS Catalina for AmberTools 18/19

I was trying to install AmberTools on my macOS Catalina Installation. Running ./configure -macAccelerate clang gave me an error that it could not find X11 libraries, even though locate libXt showed that my installation was correct.


Could not find the X11 libraries; you may need to edit config.h
   to set the XHOME and XLIBS variables.
Error: The X11 libraries are not in the usual location !
       To search for them try the command: locate libXt
       On new Fedora OS's install the libXt-devel libXext-devel
       libX11-devel libICE-devel libSM-devel packages.
       On old Fedora OS's install the xorg-x11-devel package.
       On RedHat OS's install the XFree86-devel package.
       On Ubuntu OS's install the xorg-dev and xserver-xorg packages.

          ...more info for various linuxes at

       To build Amber without XLEaP, re-run configure with '-noX11:
            ./configure -noX11 --with-python /usr/local/bin/python3 -macAccelerate clang
Configure failed due to the errors above!

I searched on Google for a solution. Sadly, there was not even a single thread which had a solution about this error.

The Fix

Simply reinstalling XQuartz using homebrew fixed the error brew cask reinstall xquartz

If you do not have XQuartz installed, you need to run brew cask install xquartz