Honesty and transparency can be incredibly powerful. At a good workplace they will be valued. If your workplace is not a good one, better to find that out as so

Honesty and transparency can be incredibly powerful. At a good workplace they will be valued. If your workplace is not a good one, better to find that out as soon as possible. Talk to your boss if he is still around, or talk to your boss' boss if not. Try to be open about your emotions. "I am feeling nervous about the Epicor upgrade". Paradoxically, you should confidently express what your anxieties are. Explain as much as you can about why: "I think I need more information to understand if this is something I can do, and what to do if something goes wrong". If you are in a junior role and you're feeling like this, it's almost certainly not your fault. Your only responsibility is to speak up about how you're feeling. Realising this can be liberating.