This question is very broad.
You may need to check your plugins for new versions which add changes for newer Cordova versions. Plugins usually should work for new versions but some versions contain breaking changes. You can expect breaking changes in major version bumps (like fro 7 to 8, 8 to 9 etc).
Make sure to check the release notes of Cordova and all plugins if something breaks. Backup your app and try updating. Removing and adding the platforms fixes some issues.
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