Links through Dashboard give 404 error

I am getting the ‘Oops! That page cant be found’ error trying to open stuff from my Dashboard Menu. Posts, Pages, Woocommerce->Orders, Woocommerce->Coupons, Products. When I click on these in the Dashboard menu, they all open the error page. Rest of the Menu works fine.

So far I have tried deactivating and activating plugins one by one to no avail.

This began around the time i was bulk updating my orders statuses.
Error logs show the following-
[16-Jan-2019 09:21:03 UTC] PHP Notice: Trying to get property of non-object in /home/ingressr/public_html/wp/wp-content/themes/astrid/functions.php on line 269

I reinstalled wordpress version 5.0.3 from Updates menu, and the 404 errors were resolved.
However i was able to reproduce the issue.
I go to woocommerce orders then try to bulk update orders. The action timed out and gave a 500 error. And then dashboard menu links gave 404 again.
Reinstalled wordpress update again and issue was resolved.
I am not sure if this is a wordpress issue or theme issue or server issue.
Any kind of advise or help would be great.

My website is

Thanks in advance!
Edit: forgot to mention that Frontend does not give any 404…the website loads fine overall.

Not really sure if it’s an issue with the theme. Because theme only does layout styling – there’s no code to change the backend system. To verify it yourself, you can try temporarily switching to one of default WordPress themes.