Hi Percy,
This error is very often caused by demand which grows too fast for endogenous capacity expansion calculations to keep pace.
I'd recommend disabling (unchecking) Transformation & Resources in Basic Params, and then viewing results. This will show you if, and where, your demand for electricity is growing extremely rapidly. Fix the problem, then re-enable Transformation & Resources in Basic Params before viewing results a second time to confirm that the problem is fixed.
Best,
Taylor