Error messages after updates

Hi!

After an update round I now get error messages in the WP backend, but also on many pages of the website. Whenever I deactivate Events Manager plugin, those messages disappear.

Best and thx for your feedback, Markus

Warning: preg_match(): Compilation failed: quantifier does not follow a repeatable item at offset 1 in /home/.sites/838/site2533937/web/wp-includes/class-wp.php on line 238 Warning: preg_match(): Compilation failed: quantifier does not follow a repeatable item at offset 1 in /home/.sites/838/site2533937/web/wp-includes/class-wp.php on line 239 Warning: preg_match(): Compilation failed: quantifier does not follow a repeatable item at offset 1 in /home/.sites/838/site2533937/web/wp-includes/class-wp.php on line 238 Warning: preg_match(): Compilation failed: quantifier does not follow a repeatable item at offset 1 in /home/.sites/838/site2533937/web/wp-includes/class-wp.php on line 239 Warning: preg_match(): Compilation failed: quantifier does not follow a repeatable item at offset 1 in /home/.sites/838/site2533937/web/wp-includes/class-wp.php on line 238 Warning: preg_match(): Compilation failed: quantifier does not follow a repeatable item at offset 1 in /home/.sites/838/site2533937/web/wp-includes/class-wp.php on line 239 Warning: preg_match(): Compilation failed: quantifier does not follow a repeatable item at offset 1 in /home/.sites/838/site2533937/web/wp-includes/class-wp.php on line 238 Warning: preg_match(): Compilation failed: quantifier does not follow a repeatable item at offset 1 in /home/.sites/838/site2533937/web/wp-includes/class-wp.php on line 239 Warning: preg_match(): Compilation failed: quantifier does not follow a repeatable item at offset 1 in /home/.sites/838/site2533937/web/wp-includes/class-wp.php on line 238 Warning: preg_match(): Compilation failed: quantifier does not follow a repeatable item at offset 1 in /home/.sites/838/site2533937/web/wp-includes/class-wp.php on line 239 Warning: preg_match(): Compilation failed: quantifier does not follow a repeatable item at offset 1 in /home/.sites/838/site2533937/web/wp-includes/class-wp.php on line 238 Warning: preg_match(): Compilation failed: quantifier does not follow a repeatable item at offset 1 in /home/.sites/838/site2533937/web/wp-includes/class-wp.php on line 239 Warning: preg_match(): Compilation failed: quantifier does not follow a repeatable item at offset 1 in /home/.sites/838/site2533937/web/wp-includes/class-wp.php on line 238 Warning: preg_match(): Compilation failed: quantifier does not follow a repeatable item at offset 1 in /home/.sites/838/site2533937/web/wp-includes/class-wp.php on line 239

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