Add to Menu in Customizer not working

I'm not sure if I'm having the same issue but when I select Customize under Appearence I Get this: /mywebsite.com/wp-admin/customize.php?return=%2Fwp-admin%2Findex.php with a blank page. I can't use the customize option. It was working before I upgraded to the new WP.

To the new WP, or the new GeneratePress?

Make sure you're using GP Premium 1.2.90 and GP 1.3.40.

If you are, try #1 on this page: https://generatepress.com/knowledgebase/debugging/

Thanks for the reply Tom. I updated to the new GP 1.3.40 now, with WP 4.6.1, and now get this error when I select
Customize

http://www/wp-admin/customize.php?return=%2Fwp-admin%2Fplugins.php%3Fdeactivate%3Dtrue%26plugin_status%3Dall%26paged%3D1%26s%3D

Any ideas?

sorry, it wasn't suppose to be a link. I jsut wanted to add the URL after my website

/wp-admin/customize.php?return=%2Fwp-admin%2Fplugins.php%3Fdeactivate%3Dtrue%26plugin_status%3Dall%26paged%3D1%26s%3D

Now I'm just deactivating all plugins except for GP Premium.. and I get this

/wp-admin/customize.php?url=http%3A%2F%2Fwww.mywebsiteurl.com%2F

I am currently using GP Theme 1.3.40, GP Premium 1.2.90, WP 4.6.1

I can't see the error messages at those URLs as I'm not logged into your site.

Are you getting any specific errors you can share here?

no. it's just a blank page. It's weird, right?

I'm doing a new install on a new domain and will try to replicate this error.

Could be a couple things.

1. Increase your PHP memory limit: https://generatepress.com/knowledgebase/increasing-memory-limit/
2. You could have a PHP error not displaying. Check your error_log file (or ask your server support to do it for you).

Let me know :)

I installed a fresh copy of everything, theme and plugins, on a new domain and same godaddy shared hosting, and it works. Any thoughts?

Is there anyway to get the older GP Premium. I think it was 1.28.9

There is, but it's not recommended. The latest version should always be used as GP (free theme) and GP Premium would hand in hand.

Did you try what I pointed out here?: https://generatepress.com/forums/topic/add-to-menu-in-customizer-not-working/page/2/#post-232845

Yes I tried both. I increased to 128 and just check out the error log (which I don't know what i means)

[06-Oct-2016 15:28:58 UTC] PHP Fatal error: Call to undefined function apply_filters() in /home/2/public_html/url.com/wp-includes/load.php on line 317

any ideas?

* i removed my personal url and replaced with the word "url.com"

apply_filters() is a core WordPress function, it should absolutely be defined.

You might have a corrupted version of WordPress caused by an incomplete update.

It's worth clicking the "Re-Install Now" button in "Dashboard > Updates".