COMSOL Multiphysics™

TABLE 2-7: SOLVER ERROR MESSAGES IN LOG WINDOW
SOLVER ERROR MESSAGE
Maximum number of
Newton iterations
reached
No convergence, even
when using the minimum
damping factor
Nonlinear solver did not
converge
Not all eigenvalues
returned
Not all parameter steps
returned
Predicted solution guess
leads to undefined
function value
EXPLANATION
The nonlinear solver could not reduce the error below the
desired tolerance in the specified maximum number of
iterations. This is sometimes a sign that the Jacobian is not
complete or badly scaled. It may even be almost singular, if
the system is underdetermined. If the returned solution
seems reasonable, it may be enough to restart the solver
with this solution as the initial guess.
The nonlinear solver reduced the damping factor below
the minimum value allowed. The solver reduces the
damping factor each time a computed step did not lead to
a decrease in the error estimate. Make sure the model is
well-posed, in particular that there are enough equations
and boundary conditions to determine all degrees of
freedom. If the model is well-posed, it should have one or
more isolated solutions. In that case, the error is probably
due to the initial guess being too far from any solution.
During a time-dependent solution, the nonlinear iteration
failed to converge despite reducing the time step to the
minimum value allowed. Usually, the error is related to the
algebraic part of a DAE. For example, the algebraic
equations can have reached a turning point or bifurcation
point. The error can also appear when the algebraic
equations do not have a unique solution consistent with
the given initial conditions. Make sure algebraic equations
have consistent initial values and that they have a unique
solution for all times and values reached by the other
variables.
When the eigenvalue solver terminated (stopped by the
user or due to an error), it had not found the requested
number of eigenvalues. The eigenvalues returned can be
trusted.
After premature termination of the parametric solver, only
some of the requested solutions have been computed.
The solver computes the initial guess for the new
parameter value based on the solution for the previous
parameter value. This initial guess led to an undefined
mathematical operation. Try using another Predictor on
the Parametric tab of Solver Parameters.
ERROR MESSAGES | 423