in PLAXIS (2D or 3D) typically indicates a numerical singularity during the calculation process. The solver (often the core solver or a direct solver like PARDISO) encounters a mathematically impossible operation—most commonly, division by zero or a nearly singular stiffness matrix.

While less common for the initial error message, material properties can lead to singularities during the calculation.

or

: Error 111 is a solver-level numerical exception – always a symptom of model ill-conditioning, not a software crash. Systematic debugging will resolve it in most cases.