mysite.com/tags = 404

Hi,

After setting permalinks when I type in

https://mysite.com/tags or https://mysite.com/topics

I get a 404: Page Not Found error.

all other permalinks work fine like

hyyp://mysite.com/tags/some-tag

This happens after a default install with no
plugins activated and using the default WordPress theme.

In the code base on the permalinks page
for tags I am using /tags/
which always reverts to just tags after saving.

Before setting up permalinks when I enter

https://mysite.com/tags

It displays the hello world page.

Any tips or help to fix would be appreciated, I really wouldn’t
care but Google Adsense is giving me blocked URL messages in
site diagnostics.

Thanks

Marc