Unable to upgrade from 4.0.7 to 4.4.1

Hi,

When I upgrade from 4.0.7 to 4.4.1, I get the following error message

Warning: preg_match() expects parameter 2 to be string, array given in /hermes/bosnacweb04/bosnacweb04aj/b716/ipg.selfhelpforlifecom/wp-admin/includes/class-wp-upgrader.php on line 258 Warning: file_exists() expects parameter 1 to be a valid path, array given in /hermes/bosnacweb04/bosnacweb04aj/b716/ipg.selfhelpforlifecom/wp-admin/includes/class-wp-upgrader.php on line 258 Warning: strip_tags() expects parameter 1 to be string, array given in /hermes/bosnacweb04/bosnacweb04aj/b716/ipg.selfhelpforlifecom/wp-admin/includes/class-bulk-upgrader-skin.php on line 61 Downloading update from …
Warning: parse_url() expects parameter 1 to be string, array given in /hermes/bosnacweb04/bosnacweb04aj/b716/ipg.selfhelpforlifecom/wp-admin/includes/file.php on line 970 Warning: preg_split() expects parameter 2 to be string, array given in /hermes/bosnacweb04/bosnacweb04aj/b716/ipg.selfhelpforlifecom/wp-includes/kses.php on line 1325 Warning: strtolower() expects parameter 1 to be string, array given in /hermes/bosnacweb04/bosnacweb04aj/b716/ipg.selfhelpforlifecom/wp-includes/http.php on line 517 Warning: strtolower() expects parameter 1 to be string, array given in /hermes/bosnacweb04/bosnacweb04aj/b716/ipg.selfhelpforlifecom/wp-includes/http.php on line 517

An error occurred while updating Enfold: Download failed. A valid URL was not provided.

I have already tried the 2 solutions explained here, but it didn’t work for me – https://kriesi.at/support/topic/can-not-update-to-enfold-4-4-1-on-all-our-websites/#post-999790

I haven’t yet tried updating the theme via FTP, because I was concerned that I could lose custom CMS and other Enfold settings. Please advice if this would be the case if I updated via FTP?

Thanks

Paul