IRR assumes that the discount rate will be the same throughout, which is not the case. NPV will defer over the years, given the cash inflows and outflows.
The internal rate of return may offer several solutions that may be difficult to analyze and confusing.
IRR can generate a negative answer which may be difficult to analyze and offer sufficient interpretation.
A positive net present value indicates wealth maximization for shareholders, while a negative present value implies a reduction in shareholders' wealth. This, however, does not apply to the internal rate of return.