Undefined variable error in theme option after updating theme [closed]

@pzstar it is a good approach to check if your variables are assigned a value or not. If a variable or an index in an array is not declared/assigned then you’d probably get such error.
I would suggest you to use isset().

<input id="welcome_post_char" type="text" name="abc_options[welcome_post_char]" value="<?php echo (isset($settings['welcome_post_char']))? esc_attr($settings['welcome_post_char'],'abc'): ''}; ?>">