Wordpress URL issues after update to 5.5.1

Question

I updated my Wordpress Website to version 5.5.1 I noticed that some URLs changed.

Bevor the update my Urls looked like this:

• Links to the category page: my/website/category/my-category-name
• Links to the articles: my/website/category/my-article-name

After the update I have it this way

• Links to the category page: my/website/my-category-name (note that /category/ is gone)
• Links to the articles: my/website/category/my-article-name

My Permalink settings in Wordpress:

• The permalinks are set to show the include the category base (): /%category%/%postname%/.
• The optional area are blank to make use wordpress default settings.

I did some testing with those settings, such as trying to set different names for the category base, but it diddn't seem to have any effect. How can I restore the the old URL structure, so that /category/ is included in the category URLs again? Any ideas on how to tackle this?

Thanks in advance

Answer 1

Someone stored wrong data in the root directory that causes this issue.