If you had already installed an extension for SEO (metaseo or seo_basics) you can migrate properties like the browser title or the canonical URL. Therefor you have to install cs_seo < 5.0 and run the update script.
After that you can delete the other SEO extension and update your database.
Page properties in TYPO3 v9¶
If you use TYPO3 v8 and want to update to TYPO3 v9 or higher, please use cs_seo version 4, to migrate the page properties from cs_seo to core, e.g ‘tx_csseo_title’ to ‘seo_title’.
From older versions¶
Please take a look at our _changelog.