Error in rayleigh frequency and errors in solver

Can you please attach the model ?

Error is still persisting 

Thank you! It worked

Such type of errors are usually caused by the instabilities in the model. In your case, there are many improperly connected members, which lead to the instabilities. You can identify these parts by going to Utilities -> Structure Tools -> Multiple Structures. So basically, first of all you need to make sure that all members in the structure are properly connected. To fix that, select all members in the model and go to Geometry -> Intersect Selected Beams -> Intersect.