Hi,
I haven’t seen this issue before, can you try to install and activate WP Safe Mode to narrow down the problem and see if this is a possible plugin or theme conflict? WP Safe Mode will virtually deactivate other plugins and revert back to the default theme you set. (see WP safe mode settings)
https://wordpress.org/plugins/wp-safe-mode/
Unfortunately I had to get the website running so I took a different path. I installed a copy of the site on another server and disabled all plugins. I continued to get the error regardless of which plugins were activated. I suspected this was related to the Wordfence plugin which was causing an error after an update. The Wordfence plugin would not activate because”it was generatring an error”. Despite un-installing Wordfence the PHP error persisted. I then installed Wordfence Assistant plugin and used it to remove all traces of Wordfence. Afterwards I was able to activate Events Manager without any PHP error. I was also able to re-intall Wordfence without any further problems. I don’t know why it happened but it is working now.
