The inventory window screen flashes but nothing happens when clicking Save and Close.

Disable the inventory module and enable

1. Go to Setup, User Preferences, View.
2. Remove the checkmarks in front of Inventory & Services for Pages and Icon Windows.
3. Click OK.
4. Go back to Setup, User Preferences, View.
5. Put the checkmarks back in front of Inventory & Services for Pages and Icon Windows.
6. Click OK.
7. Verify inventory items will save.

Reset the passwords

1. Open Sage 50 in single-user mode with the sysadmin user
2. Go to Setup / Setup Users
3. Enter the sysadmin password
4. Note down the list of users or take a screenshot of the setup screen (because you will have to recreate these users)
5. One by one, select each user and click on Remove User, except the sysadmin user
6. Then select sysadmin user and click on Modify User
7. Remove the sysadmin password by entering a character in the Enter Password box then press Backspace key so that the password is blank and do the same procedure on Re-enter Password box and click on OK
8. Close Sage 50 then open it again
9. Recreate user names and passwords, but use unique password for each user (Setup, Setup Users)
10. Try adding your inventory item now.