Clicking links in pdfs opened with Okular opens Abiword (instead of the default browser)

The answer by @Marius is correct. It helped me. Just a clarification.

Run kcmshell4 filetypes or kcmshell5 filetypes in a console or by Alt+F2. File Associations - KDE Control Module will open.
Search for html and select the file type text/html.
Move the application name you want to be a default for html in the "Application Preference Order" to the top.

For newer KDE versions you might need to run:

kcmshell4 componentchooser

and set the "Web Browser" to the command of your preferred browser.

This worked on Arch Linux, at least.

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