I found a solution. I'm not sure if it's the proper way of fixing the error code, but here's what I did.
- Open the article that you want to edit.
- You'll see a list of option tabs (Content, Images and Links, Options, Publishing, Configure Edit Screen)
- Click on Publishing
- Scroll down to Created By
- Choose your profile name (because on quick install, fake users are set up, so find your profile)
- Select your profile as the creator of the file.
- Save and close
Can't change the user ID here, which apparently has to be done in the database, but the above steps turns off the error, and now the page will save edits.
Warning: Don't keep editing a page that has the error code! If you do, your changes won't be saved and you have to start all over again with your edits. Grrrrrrrrrrrrrrrrrrrrrr!