"Cannot modify headers" during export settings

Dear Forum users,

when I try to export the Yoast Seo settings i get the following PHP errors:

Warning: Cannot modify header information - headers already sent by (output started at /thepath/wp-admin/includes/template.php:1953) in /thepath/wp-content/plugins/wordpress-seo/admin/class-export.php on line 253

Warning: Cannot modify header information - headers already sent by (output started at /thepath/wp-admin/includes/template.php:1953) in /thepath/wp-content/plugins/wordpress-seo/admin/class-export.php on line 254

Warning: Cannot modify header information - headers already sent by (output started at /thepath/wp-admin/includes/template.php:1953) in /thepath/wp-content/plugins/wordpress-seo/admin/class-export.php on line 255

Warning: Cannot modify header information - headers already sent by (output started at /thepath/wp-admin/includes/template.php:1953) in /thepath/wp-content/plugins/wordpress-seo/admin/class-export.php on line 256
PK �V�HbR�� settings.ini�WɎ�6��+}J��l^l�N� ��@I�D�D$5���%���REj��=���KK]_��ǟ·���iR�i�n/�291��������кnyIy���_���ͻ��cݖ��w�u&�0+c�~��٦*��j���g�����N��m��$�ik�MM�*���� �����" �$��Ԣ(�e<code>����3�wD)&�:��Nƙ��r�ie-H�7g���f{���n�Y���4x���N&B%:|�0 r�IZS����E<��W��?���A�/T�o0NE���iu�}�7iN�G&�E�H}iB����[T)�t��h�g�g鳫���szu�<�.�3�����K��/���� M��K0�����J˾O�Xd��T�IZU�Σ�zr����& �2�n��*w�֜�(}šq��P@�,�R�;tB쇑�HYٳ(�-�]�i�Q4c�u�c٦5�U~֨Y;�j����,��r63ƺ�����P���;h3����5�m����\���ִ�W5��Z/w�)��������ЃJ�����0�K I������ P,�n��x}�LJ_� N\G���k}i�Մ�-��͇럝�z�a� �_2RעL�M����7{ǢU ���ex��E3�.kp�a��\%��&�N���(���</code>{\��x���)��Gq����/���O!���Ԏ�FÊ�P5 -&�᣽��;���Х�3]�����${{��t�hyH���B�L��)�h<code>�)�� �*��8���n��|�Yd∦���H�p.pY�</code>���?���l���_���m4�ns�ǃ���<��J�@�����‡����$<�#{��@�x&x+S,m�����l���C�����u��G�R��u�����D۬���m+Z�� �w\E�v��)=�X߂� <γh�#�

Don’t know what to do. I downloaded a fresh version of the template.php from WordPress 4.5.3 but there is no difference betweeen the new file and mine – as expected.

Thanks in advance!
Kind regards
-reeve

https://wordpress.org/plugins/wordpress-seo/