Demonstration of error message on empty rows

test.log

Solver command line: ['/home/qtothec/.solvers/ampl.linux64/conopt', '-s', 'test.nl', 'outlev=3']

outlev=3
outlev=3

 ** Fatal Error **  There are empty rows in the model.

constraint _scon[3]: Row is empty.

  The model has 1 empty row(s).


 CONOPT time Total                            0.000 seconds
   of which: Function evaluations             0.000 =  0.0%
             1st Derivative evaluations       0.000 =  0.0%

CONOPT error: Status not called.

test.nl

g3 1 1 0	# problem unknown
 2 3 1 0 3 	# vars, constraints, objectives, ranges, eqns
 0 0 0 0 0 0	# nonlinear constrs, objs; ccons: lin, nonlin, nd, nzlb
 0 0	# network constraints: nonlinear, linear
 0 0 0 	# nonlinear vars in constraints, objectives, both
 0 0 0 1	# linear network variables; functions; arith, flags
 0 0 0 0 0 	# discrete variables: binary, integer, nonlinear (b,c,o)
 4 1 	# nonzeros in Jacobian, obj. gradient
 0 0	# max name lengths: constraints, variables
 0 0 0 0 0	# common exprs: b,c,o,c1,o1
C0
n0
C1
n0
C2
n0
O0 0
n0
x2
0 4.0
1 2.0
r
4 0.0
4 2.0
4 0.0
b
2 0
2 0
k1
2
J0 2
0 1
1 -2
J1 2
0 1
1 -1
G0 1
0 1

test.py

from __future__ import division
from pyomo.environ import *

m = ConcreteModel()

nlpsolver = SolverFactory('conopt')
nlpsolver.options['outlev'] = 3

i = m.i = RangeSet(3)

v = m.v = Var(i, domain=NonNegativeReals, initialize=0)

def def_constr(model, i):
	if i == 1:
		return v[1] == v[2] * v[3]
	if i == 2:
		return v[1] == v[2] + v[3]
	if i == 3:
		return v[2] == 2
m.c = Constraint(i, rule=def_constr)

m.obj = Objective(expr=v[1], sense=minimize)

nlpsolver.solve(m, tee=True, keepfiles=True)

m.display()

# Running with the new conditions below results in
#  ** Fatal Error **  There are empty rows in the model.

v[2].fix(2)

nlpsolver.solve(m, tee=True, keepfiles=True)

test.sol

CONOPT error: Status not called.

Options
3
1
1
0
3
0
2
0
objno 0 531
suffix 0 2 8 0 0
sstatus
0 -1073559336
1 32545
suffix 1 2 8 0 0
sstatus
0 -1073559336
1 32545