I met just same probelm too when I try to install nodebb last day. I can upload favicon but can't upload any other images. I used the same centos7 and v12.15.0 node.js. I looked up the installation log, it shows some modules did not installed well. For me it were sharp and some other modules. I guess it's the sharp module which is used to crop the images uploaded caused this problem. Sharp module need 'CXXABI_1.3.8' to compile and my default yum source did not have the gcc version needed. Maybe you can upgrade your gcc version and try reinstalling it by using "npm install sharp"? Hope this can help.