Negative eigen value error during fatigue simulation in Abaqus?

Hello everyone,

I am doing a strain-controlled low cycle fatigue simulation on Abaqus, where displacement is applied as the load with triangular waveform amplitude, and in return, the strain should be controlled throughout the simulation.

But after some time, there is excessive deformation, and the strain is out of control. The message file contains the following warnings:

***WARNING: THE SYSTEM MATRIX HAS 3 NEGATIVE EIGENVALUES.

ASYNCHRONOUS OUTPUT DATABASE FRAME FLUSH STARTED

Can anyone help me out with this issue?