wp cerber fatal error

Hi, I was stuck with wp cerber and I removed the plugin by ftp, but now I can not reactivate it anymore?
I have the following error message
(Fatal error: Uncaught Error: [] operator not supported for strings in /homepages/45/d288076581/htdocs/wp-content/plugins/wp-cerber/common.php:1026 Stack trace: #0 /homepages/45/d288076581/htdocs/wp-content/plugins/wp-cerber/cerber-load.php(4290): cerber_admin_message(‘apply_filters(”, Array) #3 /homepages/45/d288076581/htdocs/wp-includes/plugin.php(453): WP_Hook->do_action(Array) #4 /homepages/45/d288076581/htdocs/wp-admin/plugins.php(180): do_action(‘activate_wp-cer…’) #5 {main} thrown in /homepages/45/d288076581/htdocs/wp-content/plugins/wp-cerber/common.php on line 1026

regards
Gil

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