How to trace the cause of these PHP notices and warnings for class-wp-query.php?

Question

My WordPress debug.log file is filling up with these PHP notices, alternately with a gap of about 15 minutes and then of several hours…

[23-Mar-2018 05:33:00 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3736
[23-Mar-2018 05:33:00 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3738
[23-Mar-2018 05:33:00 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3740
[23-Mar-2018 05:33:00 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3736
[23-Mar-2018 05:33:00 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3738
[23-Mar-2018 05:33:00 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3740

There was no stack trace that allowed me to understand more about the source of the notice. So I installed Xdebug on the server, and set it to “5”. Now debug.log is filling up with a more detailed log. Here is the trace equivalent of the above…

[27-Mar-2018 04:30:26 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3736
[27-Mar-2018 04:30:26 UTC] PHP Stack trace:
[27-Mar-2018 04:30:26 UTC] PHP   1. {main}() /home/mysite/public_html/index.php:0
[27-Mar-2018 04:30:26 UTC] PHP   2. require() /home/mysite/public_html/index.php:17
[27-Mar-2018 04:30:26 UTC] PHP   3. require_once() /home/mysite/public_html/wp-blog-header.php:19
[27-Mar-2018 04:30:26 UTC] PHP   4. do_action() /home/mysite/public_html/wp-includes/template-loader.php:12
[27-Mar-2018 04:30:26 UTC] PHP   5. WP_Hook->do_action() /home/mysite/public_html/wp-includes/plugin.php:453
[27-Mar-2018 04:30:26 UTC] PHP   6. WP_Hook->apply_filters() /home/mysite/public_html/wp-includes/class-wp-hook.php:310
[27-Mar-2018 04:30:26 UTC] PHP   7. redirect_canonical() /home/mysite/public_html/wp-includes/class-wp-hook.php:286
[27-Mar-2018 04:30:26 UTC] PHP   8. is_front_page() /home/mysite/public_html/wp-includes/canonical.php:433
[27-Mar-2018 04:30:26 UTC] PHP   9. WP_Query->is_front_page() /home/mysite/public_html/wp-includes/query.php:410
[27-Mar-2018 04:30:26 UTC] PHP  10. WP_Query->is_page() /home/mysite/public_html/wp-includes/class-wp-query.php:3674
[27-Mar-2018 04:30:26 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3738
[27-Mar-2018 04:30:26 UTC] PHP Stack trace:
[27-Mar-2018 04:30:26 UTC] PHP   1. {main}() /home/mysite/public_html/index.php:0
[27-Mar-2018 04:30:26 UTC] PHP   2. require() /home/mysite/public_html/index.php:17
[27-Mar-2018 04:30:26 UTC] PHP   3. require_once() /home/mysite/public_html/wp-blog-header.php:19
[27-Mar-2018 04:30:26 UTC] PHP   4. do_action() /home/mysite/public_html/wp-includes/template-loader.php:12
[27-Mar-2018 04:30:26 UTC] PHP   5. WP_Hook->do_action() /home/mysite/public_html/wp-includes/plugin.php:453
[27-Mar-2018 04:30:26 UTC] PHP   6. WP_Hook->apply_filters() /home/mysite/public_html/wp-includes/class-wp-hook.php:310
[27-Mar-2018 04:30:26 UTC] PHP   7. redirect_canonical() /home/mysite/public_html/wp-includes/class-wp-hook.php:286
[27-Mar-2018 04:30:26 UTC] PHP   8. is_front_page() /home/mysite/public_html/wp-includes/canonical.php:433
[27-Mar-2018 04:30:26 UTC] PHP   9. WP_Query->is_front_page() /home/mysite/public_html/wp-includes/query.php:410
[27-Mar-2018 04:30:26 UTC] PHP  10. WP_Query->is_page() /home/mysite/public_html/wp-includes/class-wp-query.php:3674
[27-Mar-2018 04:30:26 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3740
[27-Mar-2018 04:30:26 UTC] PHP Stack trace:
[27-Mar-2018 04:30:26 UTC] PHP   1. {main}() /home/mysite/public_html/index.php:0
[27-Mar-2018 04:30:26 UTC] PHP   2. require() /home/mysite/public_html/index.php:17
[27-Mar-2018 04:30:26 UTC] PHP   3. require_once() /home/mysite/public_html/wp-blog-header.php:19
[27-Mar-2018 04:30:26 UTC] PHP   4. do_action() /home/mysite/public_html/wp-includes/template-loader.php:12
[27-Mar-2018 04:30:26 UTC] PHP   5. WP_Hook->do_action() /home/mysite/public_html/wp-includes/plugin.php:453
[27-Mar-2018 04:30:26 UTC] PHP   6. WP_Hook->apply_filters() /home/mysite/public_html/wp-includes/class-wp-hook.php:310
[27-Mar-2018 04:30:26 UTC] PHP   7. redirect_canonical() /home/mysite/public_html/wp-includes/class-wp-hook.php:286
[27-Mar-2018 04:30:26 UTC] PHP   8. is_front_page() /home/mysite/public_html/wp-includes/canonical.php:433
[27-Mar-2018 04:30:26 UTC] PHP   9. WP_Query->is_front_page() /home/mysite/public_html/wp-includes/query.php:410
[27-Mar-2018 04:30:26 UTC] PHP  10. WP_Query->is_page() /home/mysite/public_html/wp-includes/class-wp-query.php:3674
[27-Mar-2018 04:30:26 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3736
[27-Mar-2018 04:30:26 UTC] PHP Stack trace:
[27-Mar-2018 04:30:26 UTC] PHP   1. {main}() /home/mysite/public_html/index.php:0
[27-Mar-2018 04:30:26 UTC] PHP   2. require() /home/mysite/public_html/index.php:17
[27-Mar-2018 04:30:26 UTC] PHP   3. require_once() /home/mysite/public_html/wp-blog-header.php:19
[27-Mar-2018 04:30:26 UTC] PHP   4. do_action() /home/mysite/public_html/wp-includes/template-loader.php:12
[27-Mar-2018 04:30:26 UTC] PHP   5. WP_Hook->do_action() /home/mysite/public_html/wp-includes/plugin.php:453
[27-Mar-2018 04:30:26 UTC] PHP   6. WP_Hook->apply_filters() /home/mysite/public_html/wp-includes/class-wp-hook.php:310
[27-Mar-2018 04:30:26 UTC] PHP   7. redirect_canonical() /home/mysite/public_html/wp-includes/class-wp-hook.php:286
[27-Mar-2018 04:30:26 UTC] PHP   8. redirect_canonical() /home/mysite/public_html/wp-includes/canonical.php:532
[27-Mar-2018 04:30:26 UTC] PHP   9. is_front_page() /home/mysite/public_html/wp-includes/canonical.php:433
[27-Mar-2018 04:30:26 UTC] PHP  10. WP_Query->is_front_page() /home/mysite/public_html/wp-includes/query.php:410
[27-Mar-2018 04:30:26 UTC] PHP  11. WP_Query->is_page() /home/mysite/public_html/wp-includes/class-wp-query.php:3674
[27-Mar-2018 04:30:26 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3738
[27-Mar-2018 04:30:26 UTC] PHP Stack trace:
[27-Mar-2018 04:30:26 UTC] PHP   1. {main}() /home/mysite/public_html/index.php:0
[27-Mar-2018 04:30:26 UTC] PHP   2. require() /home/mysite/public_html/index.php:17
[27-Mar-2018 04:30:26 UTC] PHP   3. require_once() /home/mysite/public_html/wp-blog-header.php:19
[27-Mar-2018 04:30:26 UTC] PHP   4. do_action() /home/mysite/public_html/wp-includes/template-loader.php:12
[27-Mar-2018 04:30:26 UTC] PHP   5. WP_Hook->do_action() /home/mysite/public_html/wp-includes/plugin.php:453
[27-Mar-2018 04:30:26 UTC] PHP   6. WP_Hook->apply_filters() /home/mysite/public_html/wp-includes/class-wp-hook.php:310
[27-Mar-2018 04:30:26 UTC] PHP   7. redirect_canonical() /home/mysite/public_html/wp-includes/class-wp-hook.php:286
[27-Mar-2018 04:30:26 UTC] PHP   8. redirect_canonical() /home/mysite/public_html/wp-includes/canonical.php:532
[27-Mar-2018 04:30:26 UTC] PHP   9. is_front_page() /home/mysite/public_html/wp-includes/canonical.php:433
[27-Mar-2018 04:30:26 UTC] PHP  10. WP_Query->is_front_page() /home/mysite/public_html/wp-includes/query.php:410
[27-Mar-2018 04:30:26 UTC] PHP  11. WP_Query->is_page() /home/mysite/public_html/wp-includes/class-wp-query.php:3674
[27-Mar-2018 04:30:26 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3740
[27-Mar-2018 04:30:26 UTC] PHP Stack trace:
[27-Mar-2018 04:30:26 UTC] PHP   1. {main}() /home/mysite/public_html/index.php:0
[27-Mar-2018 04:30:26 UTC] PHP   2. require() /home/mysite/public_html/index.php:17
[27-Mar-2018 04:30:26 UTC] PHP   3. require_once() /home/mysite/public_html/wp-blog-header.php:19
[27-Mar-2018 04:30:26 UTC] PHP   4. do_action() /home/mysite/public_html/wp-includes/template-loader.php:12
[27-Mar-2018 04:30:26 UTC] PHP   5. WP_Hook->do_action() /home/mysite/public_html/wp-includes/plugin.php:453
[27-Mar-2018 04:30:26 UTC] PHP   6. WP_Hook->apply_filters() /home/mysite/public_html/wp-includes/class-wp-hook.php:310
[27-Mar-2018 04:30:26 UTC] PHP   7. redirect_canonical() /home/mysite/public_html/wp-includes/class-wp-hook.php:286
[27-Mar-2018 04:30:26 UTC] PHP   8. redirect_canonical() /home/mysite/public_html/wp-includes/canonical.php:532
[27-Mar-2018 04:30:26 UTC] PHP   9. is_front_page() /home/mysite/public_html/wp-includes/canonical.php:433
[27-Mar-2018 04:30:26 UTC] PHP  10. WP_Query->is_front_page() /home/mysite/public_html/wp-includes/query.php:410
[27-Mar-2018 04:30:26 UTC] PHP  11. WP_Query->is_page() /home/mysite/public_html/wp-includes/class-wp-query.php:3674
[27-Mar-2018 04:30:26 UTC] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/mysite/public_html/wp-includes/class-wp-query.php:3736) in /home/mysite/public_html/wp-includes/pluggable.php on line 1216
[27-Mar-2018 04:30:26 UTC] PHP Stack trace:
[27-Mar-2018 04:30:26 UTC] PHP   1. {main}() /home/mysite/public_html/index.php:0
[27-Mar-2018 04:30:26 UTC] PHP   2. require() /home/mysite/public_html/index.php:17
[27-Mar-2018 04:30:26 UTC] PHP   3. require_once() /home/mysite/public_html/wp-blog-header.php:19
[27-Mar-2018 04:30:26 UTC] PHP   4. do_action() /home/mysite/public_html/wp-includes/template-loader.php:12
[27-Mar-2018 04:30:26 UTC] PHP   5. WP_Hook->do_action() /home/mysite/public_html/wp-includes/plugin.php:453
[27-Mar-2018 04:30:26 UTC] PHP   6. WP_Hook->apply_filters() /home/mysite/public_html/wp-includes/class-wp-hook.php:310
[27-Mar-2018 04:30:26 UTC] PHP   7. redirect_canonical() /home/mysite/public_html/wp-includes/class-wp-hook.php:286
[27-Mar-2018 04:30:26 UTC] PHP   8. wp_redirect() /home/mysite/public_html/wp-includes/canonical.php:533
[27-Mar-2018 04:30:26 UTC] PHP   9. header() /home/mysite/public_html/wp-includes/pluggable.php:1216
[27-Mar-2018 04:30:28 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3736
[27-Mar-2018 04:30:28 UTC] PHP Stack trace:
[27-Mar-2018 04:30:28 UTC] PHP   1. {main}() /home/mysite/public_html/index.php:0
[27-Mar-2018 04:30:28 UTC] PHP   2. require() /home/mysite/public_html/index.php:17
[27-Mar-2018 04:30:28 UTC] PHP   3. require_once() /home/mysite/public_html/wp-blog-header.php:19
[27-Mar-2018 04:30:28 UTC] PHP   4. do_action() /home/mysite/public_html/wp-includes/template-loader.php:12
[27-Mar-2018 04:30:28 UTC] PHP   5. WP_Hook->do_action() /home/mysite/public_html/wp-includes/plugin.php:453
[27-Mar-2018 04:30:28 UTC] PHP   6. WP_Hook->apply_filters() /home/mysite/public_html/wp-includes/class-wp-hook.php:310
[27-Mar-2018 04:30:28 UTC] PHP   7. redirect_canonical() /home/mysite/public_html/wp-includes/class-wp-hook.php:286
[27-Mar-2018 04:30:28 UTC] PHP   8. is_front_page() /home/mysite/public_html/wp-includes/canonical.php:433
[27-Mar-2018 04:30:28 UTC] PHP   9. WP_Query->is_front_page() /home/mysite/public_html/wp-includes/query.php:410
[27-Mar-2018 04:30:28 UTC] PHP  10. WP_Query->is_page() /home/mysite/public_html/wp-includes/class-wp-query.php:3674
[27-Mar-2018 04:30:28 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3738
[27-Mar-2018 04:30:28 UTC] PHP Stack trace:
[27-Mar-2018 04:30:28 UTC] PHP   1. {main}() /home/mysite/public_html/index.php:0
[27-Mar-2018 04:30:28 UTC] PHP   2. require() /home/mysite/public_html/index.php:17
[27-Mar-2018 04:30:28 UTC] PHP   3. require_once() /home/mysite/public_html/wp-blog-header.php:19
[27-Mar-2018 04:30:28 UTC] PHP   4. do_action() /home/mysite/public_html/wp-includes/template-loader.php:12
[27-Mar-2018 04:30:28 UTC] PHP   5. WP_Hook->do_action() /home/mysite/public_html/wp-includes/plugin.php:453
[27-Mar-2018 04:30:28 UTC] PHP   6. WP_Hook->apply_filters() /home/mysite/public_html/wp-includes/class-wp-hook.php:310
[27-Mar-2018 04:30:28 UTC] PHP   7. redirect_canonical() /home/mysite/public_html/wp-includes/class-wp-hook.php:286
[27-Mar-2018 04:30:28 UTC] PHP   8. is_front_page() /home/mysite/public_html/wp-includes/canonical.php:433
[27-Mar-2018 04:30:28 UTC] PHP   9. WP_Query->is_front_page() /home/mysite/public_html/wp-includes/query.php:410
[27-Mar-2018 04:30:28 UTC] PHP  10. WP_Query->is_page() /home/mysite/public_html/wp-includes/class-wp-query.php:3674
[27-Mar-2018 04:30:28 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3740
[27-Mar-2018 04:30:28 UTC] PHP Stack trace:
[27-Mar-2018 04:30:28 UTC] PHP   1. {main}() /home/mysite/public_html/index.php:0
[27-Mar-2018 04:30:28 UTC] PHP   2. require() /home/mysite/public_html/index.php:17
[27-Mar-2018 04:30:28 UTC] PHP   3. require_once() /home/mysite/public_html/wp-blog-header.php:19
[27-Mar-2018 04:30:28 UTC] PHP   4. do_action() /home/mysite/public_html/wp-includes/template-loader.php:12
[27-Mar-2018 04:30:28 UTC] PHP   5. WP_Hook->do_action() /home/mysite/public_html/wp-includes/plugin.php:453
[27-Mar-2018 04:30:28 UTC] PHP   6. WP_Hook->apply_filters() /home/mysite/public_html/wp-includes/class-wp-hook.php:310
[27-Mar-2018 04:30:28 UTC] PHP   7. redirect_canonical() /home/mysite/public_html/wp-includes/class-wp-hook.php:286
[27-Mar-2018 04:30:28 UTC] PHP   8. is_front_page() /home/mysite/public_html/wp-includes/canonical.php:433
[27-Mar-2018 04:30:28 UTC] PHP   9. WP_Query->is_front_page() /home/mysite/public_html/wp-includes/query.php:410
[27-Mar-2018 04:30:28 UTC] PHP  10. WP_Query->is_page() /home/mysite/public_html/wp-includes/class-wp-query.php:3674
[27-Mar-2018 04:30:28 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3736
[27-Mar-2018 04:30:28 UTC] PHP Stack trace:
[27-Mar-2018 04:30:28 UTC] PHP   1. {main}() /home/mysite/public_html/index.php:0
[27-Mar-2018 04:30:28 UTC] PHP   2. require() /home/mysite/public_html/index.php:17
[27-Mar-2018 04:30:28 UTC] PHP   3. require_once() /home/mysite/public_html/wp-blog-header.php:19
[27-Mar-2018 04:30:28 UTC] PHP   4. do_action() /home/mysite/public_html/wp-includes/template-loader.php:12
[27-Mar-2018 04:30:28 UTC] PHP   5. WP_Hook->do_action() /home/mysite/public_html/wp-includes/plugin.php:453
[27-Mar-2018 04:30:28 UTC] PHP   6. WP_Hook->apply_filters() /home/mysite/public_html/wp-includes/class-wp-hook.php:310
[27-Mar-2018 04:30:28 UTC] PHP   7. redirect_canonical() /home/mysite/public_html/wp-includes/class-wp-hook.php:286
[27-Mar-2018 04:30:28 UTC] PHP   8. redirect_canonical() /home/mysite/public_html/wp-includes/canonical.php:532
[27-Mar-2018 04:30:28 UTC] PHP   9. is_front_page() /home/mysite/public_html/wp-includes/canonical.php:433
[27-Mar-2018 04:30:28 UTC] PHP  10. WP_Query->is_front_page() /home/mysite/public_html/wp-includes/query.php:410
[27-Mar-2018 04:30:28 UTC] PHP  11. WP_Query->is_page() /home/mysite/public_html/wp-includes/class-wp-query.php:3674
[27-Mar-2018 04:30:28 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3738
[27-Mar-2018 04:30:28 UTC] PHP Stack trace:
[27-Mar-2018 04:30:28 UTC] PHP   1. {main}() /home/mysite/public_html/index.php:0
[27-Mar-2018 04:30:28 UTC] PHP   2. require() /home/mysite/public_html/index.php:17
[27-Mar-2018 04:30:28 UTC] PHP   3. require_once() /home/mysite/public_html/wp-blog-header.php:19
[27-Mar-2018 04:30:28 UTC] PHP   4. do_action() /home/mysite/public_html/wp-includes/template-loader.php:12
[27-Mar-2018 04:30:28 UTC] PHP   5. WP_Hook->do_action() /home/mysite/public_html/wp-includes/plugin.php:453
[27-Mar-2018 04:30:28 UTC] PHP   6. WP_Hook->apply_filters() /home/mysite/public_html/wp-includes/class-wp-hook.php:310
[27-Mar-2018 04:30:28 UTC] PHP   7. redirect_canonical() /home/mysite/public_html/wp-includes/class-wp-hook.php:286
[27-Mar-2018 04:30:28 UTC] PHP   8. redirect_canonical() /home/mysite/public_html/wp-includes/canonical.php:532
[27-Mar-2018 04:30:28 UTC] PHP   9. is_front_page() /home/mysite/public_html/wp-includes/canonical.php:433
[27-Mar-2018 04:30:28 UTC] PHP  10. WP_Query->is_front_page() /home/mysite/public_html/wp-includes/query.php:410
[27-Mar-2018 04:30:28 UTC] PHP  11. WP_Query->is_page() /home/mysite/public_html/wp-includes/class-wp-query.php:3674
[27-Mar-2018 04:30:28 UTC] PHP Notice:  Trying to get property of non-object in /home/mysite/public_html/wp-includes/class-wp-query.php on line 3740
[27-Mar-2018 04:30:28 UTC] PHP Stack trace:
[27-Mar-2018 04:30:28 UTC] PHP   1. {main}() /home/mysite/public_html/index.php:0
[27-Mar-2018 04:30:28 UTC] PHP   2. require() /home/mysite/public_html/index.php:17
[27-Mar-2018 04:30:28 UTC] PHP   3. require_once() /home/mysite/public_html/wp-blog-header.php:19
[27-Mar-2018 04:30:28 UTC] PHP   4. do_action() /home/mysite/public_html/wp-includes/template-loader.php:12
[27-Mar-2018 04:30:28 UTC] PHP   5. WP_Hook->do_action() /home/mysite/public_html/wp-includes/plugin.php:453
[27-Mar-2018 04:30:28 UTC] PHP   6. WP_Hook->apply_filters() /home/mysite/public_html/wp-includes/class-wp-hook.php:310
[27-Mar-2018 04:30:28 UTC] PHP   7. redirect_canonical() /home/mysite/public_html/wp-includes/class-wp-hook.php:286
[27-Mar-2018 04:30:28 UTC] PHP   8. redirect_canonical() /home/mysite/public_html/wp-includes/canonical.php:532
[27-Mar-2018 04:30:28 UTC] PHP   9. is_front_page() /home/mysite/public_html/wp-includes/canonical.php:433
[27-Mar-2018 04:30:28 UTC] PHP  10. WP_Query->is_front_page() /home/mysite/public_html/wp-includes/query.php:410
[27-Mar-2018 04:30:28 UTC] PHP  11. WP_Query->is_page() /home/mysite/public_html/wp-includes/class-wp-query.php:3674
[27-Mar-2018 04:30:28 UTC] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/mysite/public_html/wp-includes/class-wp-query.php:3736) in /home/mysite/public_html/wp-includes/pluggable.php on line 1216
[27-Mar-2018 04:30:28 UTC] PHP Stack trace:
[27-Mar-2018 04:30:28 UTC] PHP   1. {main}() /home/mysite/public_html/index.php:0
[27-Mar-2018 04:30:28 UTC] PHP   2. require() /home/mysite/public_html/index.php:17
[27-Mar-2018 04:30:28 UTC] PHP   3. require_once() /home/mysite/public_html/wp-blog-header.php:19
[27-Mar-2018 04:30:28 UTC] PHP   4. do_action() /home/mysite/public_html/wp-includes/template-loader.php:12
[27-Mar-2018 04:30:28 UTC] PHP   5. WP_Hook->do_action() /home/mysite/public_html/wp-includes/plugin.php:453
[27-Mar-2018 04:30:28 UTC] PHP   6. WP_Hook->apply_filters() /home/mysite/public_html/wp-includes/class-wp-hook.php:310
[27-Mar-2018 04:30:28 UTC] PHP   7. redirect_canonical() /home/mysite/public_html/wp-includes/class-wp-hook.php:286
[27-Mar-2018 04:30:28 UTC] PHP   8. wp_redirect() /home/mysite/public_html/wp-includes/canonical.php:533
[27-Mar-2018 04:30:28 UTC] PHP   9. header() /home/mysite/public_html/wp-includes/pluggable.php:1216

I can’t quite understand what the problem is. I mean, there’s reference to canonical, to plugin.php, to blog header. I also see is_page in there.

One thing I am wondering if this relates to Advanced Custom Fields. I have an ACF field group set to display on Page edit screens. And I have written my page.php theme file to output content based on the content saved in the backend.

The site is also a child site running off WordPress Multisite, so does canonical have a role here?

I’m also aware "Cannot modify header information - headers already sent" can sometimes indicate a stray space at the end of a plugin file.

But, still, I don’t quite know where to go next with the evidence gathered.

Thanks.

0
Robert Andrews 3 years 2018-03-27T16:28:37-05:00 0 Answers 72 views 0

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