Why are people resistant to change? Short answer: because it makes sense.
Change means uncertainty. Will I like it? Will I not like it? Will I be good at it? Will I not be good at it? Will I be more secure? Will I be less secure? Will I have more status? Will I have less status? People want to know how the change will affect them. Uncertainty means there is a range of outcomes, some positive and some negative. They are understandably apprehensive, even fearful, about the negative outcomes.
So what can you as a leader do to soften the reaction to change? Communicate. A lot. Explain the what, why and how of change. Paint a picture of what similar change has meant for other organizations and individuals.
Reducing uncertainty reduces fear. You won’t eliminate it. But you can mitigate its effects.