I am rolling out an IT project, but some managers is nervous because of previous expreience, how to handle it?

Answer 1

Address his/her concerns and have a plan to deal with anything that might go wrong.
If he's worried about technical glitches, do extensive testing first, and have contingency plans and a roll-back plan in case something goes wrong.
If he's worried about user acceptance, put someone on PR to pave the way and perhaps organize training for the new system (the roll out could be part of a larger project plan, that addresses these issues).
If he's worried about a shortage of man power for the roll-out, plan everything step by step and make sure you've got all the resources you need.
In short, have him specify his worries, and address them one by one.

Answer 2

First of all you need "real" users testing it (1% to 3% of the total users to make up the testers group).. put it through its pases under the harshest of conditions... we do that on our systems and its worked well. It comes down to not causing production interruptions and assuring managment of its stability once its deployed.

Answer 3

You have a back up to get back to in case things go wrong.

You pre-tested it on a closed system, not the real net.

You had rank and file workers test it.