I contact porto support they said it is not problem causing by the theme. I spent a lot time researching the issue still can not find any solutions. PLease let me know if you have any solutions.
I agree with Porto. I don’t see how this error is related to your issue. However, a quick Google Search for your error has turned up this results
OK. Mageplaza is bit of nightmare. so after month of digging. Here is the Solution:
Go to your magento database. find a table called cms_page check a field called: mp_exclude_sitemap simply delete this field. I though when I remove magaplaza module I could just delete the field with mageplaza prefix from database. little did I know here is one with mp_ prefix. that’s not cool.
So, it seems that your issue is related to a Mageplaza module. If this does not solve your issue, I would recommend reaching out to them directly.
As a VERY OLD version of Mageplaza Layered Navigation is bundled with the Porto installation, @digitalstartup 's reply makes sense. Contacting Mageplaza support might be an idea.