a CPUP file will only update the program for the same year. You should have the install file for 2018 if that is what was running on your old computer. You will need your 2018 serial number and key code along with the Company name and the Account number. If you don't have these, open Sage 50 on your old computer. go to Help and About Sage 50, then Support Info. The first page has all that is required information. Now to get the right program  version - On the About Sage 50 first window, top line tells you the program and Version. This is where you want to end up so that your data will open. Again from your old computer, go to  C:/Sage and pick the correct version of the installer files for the version you require. If it is not there dig deeper, C:/Users/Public/Public Documents/Sage Software/Simply Accounting/ Downloads. From this list pick the version that you require. SA_20xxxCP1.exe will be the full file and SA_xxxCPUP1.exe is the update file which requires the full file of the same version year to already be installed. These files are no longer available from Sage, however, there are a number of us who maintain the files to service our clients. If you have all of the required installation information I am certain you will be able to locate the full file (for a small cost) on this forum.

Hope this helps