Limit the findings in TYPO3
Check the preferred site base against forwarding to the web server or proxy. Internal links should use the same public host form.
Where to check the setting in TYPO3
Set the preferred domain in the site base and compare the forwarding to the web server or reverse proxy. Go directly to www and non-www variants. The alternative address should lead to the preferred HTTPS address without a loop; changes to internal link fields alone do not solve a conflicting host configuration.
Example of this specific finding
Illustrative control case: The homepage unifies www and non-www, but deep articles remain accessible among both hosts with different canonicals.
follow-up audit in TYPO3
Check the preferred host version for homepage, articles and language paths. Forwarding, certificates, internal links and canonicals must support the same choice.
Derogations and scope
Both host variants can operate technically different offers. Consolidate only real variants of the same content.
Reference: TYPO3 13.4 with EXT:seo. For other major versions and own extensions, responsibilities may differ; check the actually installed output.
Classify the general error
Definition, system-independent causes and further correction examples: Track a main version across all page types