When upgrading NextCloud in Softaculous, you will get an error message after the update "The files of the app External user support (user_external) were not replaced correctly."
In your file manager edit /apps/user_external/appinfo/info.xml
From: <nextcloud min-version="13" max-version="14" />
To: <nextcloud min-version="13" max-version="15" />
Refresh the page where you update your installation and it will proceed.
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