This thread is resolved. Here is a description of the problem and solution.
Problem: After activating WPML, my site returns a fatal error.
Solution: There were a lot of errors in the debug log relating the WPML language switcher slots. When I searched the database, I found an entry in the wp_options table with the option name "wpml_language_switcher". I deleted this row from the database and I was then able to activate the WPML plugin.
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