I found a post that helped a lot at https://www.ads-software.com/support/topic/36245
1. This error might be caused by an old (pre-1.5) call for the comments.php template. Check if you have this line in your index.php:
<?php comments_template( is_single() ); // Get wp-comments.php template ?>
change it to
<?php comments_template(); // Get wp-comments.php template ?>
I made that change and the sidebar now shows up in my Pages. The color and background that sets the sidebar apart from the rest of the Page is gone (it’s all one white page), but I can live with that since it doesn’t affect the main body of my blog (only affects the Pages).
So I guess this issue is mainly resolved. Thanks for your help.