Technical explanation
Modrinth App uses an internal database to store information about your instances and settings. Updates to the app may change the database structure through a process known as migration.
When a migration is complete, a record of it is stored in the database, in a table of previously applied migrations. This allows the app to check whether the database is up-to-date or whether it needs to be updated first.
Attempting to launch an older version of the app after the migrations of the newer versions have been applied will result in an initialization error with the following message (visible under the Debug info spoiler):
migration 20240930001852 was previously applied but is missing in the resolved migrations
This safety measure prevents older versions of the app from using an updated database. Without it, the app could crash or behave unpredictably because it wouldn't understand how the newer database organizes information.
Solution
This error occurs when you're trying to run an older version of the app, possibly through an outdated shortcut or installation.
To fix this on Windows:
Open the list of installed apps in Windows Settings.
Uninstall all copies of Modrinth App (see important warning below).
Download and install the latest version from Modrinth website.
🔥 Do not check the "Delete the application data" option.
Checking this box will permanently erase all your profiles and worlds. If you're worried about accidentally selecting this option, you can back up your data by copying the entire %AppData%\ModrinthApp folder before uninstalling.
Still not working?
If the old version doesn't appear in the installed apps list, you may need to manually uninstall and remove the old files.
To do this:
Right-click the shortcut you use to open Modrinth App.
Select 📂 Open file location from the menu.
For ⊞ Start menu, this option will open the folder with all your Start menu shortcuts, so you need to find Modrinth App in there and repeat this step.
If present, run the
uninstall.exefile (remember the warning above about not deleting application data).
Delete the
Modrinth App.exeortheseus_gui.exefiles if they remain after uninstallation.
Download and install the latest version of the app from the website.
