1. Solver not found

Solvers are not distributed with Pyomo and must be installed separately by the user. In general, the solver executable must be accessible using a terminal command. For example, ipopt can only be used as a solver if the command

$ ipopt

invokes the solver. For example

$ ipopt -?
usage: ipopt [options] stub [-AMPL] [<assignment> ...]

     --  {end of options}
     -=  {show name= possibilities}
     -?  {show usage}
     -bf {read boundsfile f}
     -e  {suppress echoing of assignments}
     -of {write .sol file to file f}
     -s  {write .sol file (without -AMPL)}
     -v  {just show version}