Undefined index: page

Running a development in debug mode I received this error upon activation of your plugin: “Notice: Undefined index: page in …/wp/wp-content/plugins/simple-share-buttons-adder/simple-share-buttons-adder.php on line 342”

Looks like you need to add an isset() to that line, changing it from this:

if ($arrSettings['ssba_selected_buttons'] == '' && $_GET['page'] != 'simple-share-buttons-adder') {

To this:

if ($arrSettings['ssba_selected_buttons'] == '' && isset( $_GET['page'] ) && $_GET['page'] != 'simple-share-buttons-adder') {

https://www.ads-software.com/plugins/simple-share-buttons-adder/