opening an existing post

check your permalinks. are you using a custom structure?

Please expalin and instruct me how to solve the problem.
Thanks so much.

see if this helps: https://codex.www.ads-software.com/Using_Permalinks#Choosing_your_permalink_structure

I am facing the exact same problem. I was upgrading from 2.6 to 3.1.1 and faced that problem. I figured it was because of the big jump. So now I’m upgrading incrementally. I upgraded to 2.7 and had the exact same problem!

I have tried several different permalink settings (custom, default, different custom, etc) but it didn’t make a difference.

Any other ideas?

-Jeff

Anybody still read this thread? I’m hoping someone has an idea!

-Jeff

Give this a shot https://dre.im/if-pages-return-a-404-after-wordpress-3-1-upgrade/

@mcleodjeff deactivate all plugins and switch to default theme change your permalinks to default and then upgrade in steps

You will find instructions here

https://codex.www.ads-software.com/Updating_WordPress