No need to uninstall first. In fact, to be on the safe side I would wait until you know everything is working right on the new PC before uninstalling. You can copy the data but I recommend making a backup of your company and then restore it on the new PC. Then you know it will end up in the right location and your custom forms will be restored too.

The latest release of versions 2019, 2020, and 2021 can all be downloaded from the knowledgebase. Just scroll down to the Popular Downloads section.

Thank you, I will be installing the new PC this weekend. Thanks

I installed my original Sage 50 Premium Accounting 2019 build 26.0.00.0141

I then copied my data from the old pc to new one.

I could NOT open the company.

Should I have downloaded the 2021 version first?

My current version on the OLD PC is Accounting 2021 Build 28.0.00.0114

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There was no need to install the 2019 version. Install 2021 on the new PC and you'll be able to open your company.

Looks like it installed - Thanks

Even though I put my serial number in for the install it say un registered. Where do I go to register it, or do I need to wait until I'm completely done on the old computer?

It should prompt you to activate. It it doesn't, go to the Help menu and choose "Sage 50 Activation, Licensing, & Subscription Options."