I have reviewed your design and and the error and I have confirmed that my original statement was correct. The error you are encountering is because the mode solver has determined that the structure you have does not support a mode at 1.3um.
Looking into your design I see that your waveguide has a refractive index of 1.5 while the surrounding material has a refractive index of 2.1 which means that this structure will not support a mode and therefore why the simulation is terminating with the error.
Your waveguide should have a higher refractive index than the surrounding material.
Scott