Hmmm. I never bother to uninstall I just upgrade, on some occasions I get a message that the old database will be upgraded so that "may" be the problem.
What I would do is the following to try and see if it was a problem with the new install or a problem with the upgrade and the older database. Note. Have a look at what I would do and decide what if any steps you woulod like to try
1) Backup the current database as a safety:
Copy all the files in c:\users(username)\Appdata\local\darktable to a safe place to restore later. Note Appdata is a hiddedn directory so you need to set windows view to see hidden files
2) Delete all of the files in c:\users(username)\Appdata\local\darktable
3) Start darktable. darktable will find that the directory is empty and will assume that it is a new installation and will re-create all of the files.
If darktable has started then I know that the problem is with the database so go to step (4)
If darktable did not start than I know that the problem is with the new version of darktable so go to step (10)
4) Problem is with the databse therefore: Uninstall darktable
5) Delete all of the files in c:\users(username)\Appdata\local\darktable
6) Restore the files from my saved backup back to c:\users(username)\Appdata\local\darktable
7) Install older version of darktable and check all works ok as you should be back pre update
8) Install new version of darktable and it "should" update the database
9) Sit back and enjoy the new version you are now finished
10) The problem is with the new version not the database.
11) Uninstall darktable, download the latest and install to try again.
12) if this works then do steps 5 and 6 and see if it works
13) if there is still a problem then we need to go back to the older version as there is a problem with the new version on your PC. therefore do steps 4 5 6 and 7 to put darktable back to the old version and stay with this until another update comes along then try again.