Domain mapping connects a subsite to its own custom domain instead of the network’s default address, and when that mapping breaks — the domain not resolving, showing the wrong subsite, or SSL errors specific to the mapped domain — the cause is usually a mismatch between DNS, the mapping configuration, and what the network actually expects.
Confirm DNS for the mapped domain points correctly at your network first
Check that the mapped domain’s DNS actually points at your hosting, the same as your network’s primary domain would. A DNS-level mismatch here is one of the most common and most straightforward causes to confirm before assuming a deeper WordPress-level mapping issue.
Domain mapping errors
A subsite's mapped domain not resolving correctly, traced from DNS through to SSL coverage.
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This or something else?
| A subsite’s custom mapped domain isn’t resolving correctly, or shows the wrong content | This fix covers it |
| You want domain mapping set up for a subsite for the first time, not an existing mapping fixed | Still covered by this fix, treated as an initial setup rather than a repair |
| The issue is with the network itself, not one specific subsite’s domain mapping | Multisite network configuration errors, the broader version |
| You want an SSL certificate issue on the mapped domain addressed specifically | Worth confirming — this fix covers mapping-related SSL issues, though a broader certificate installation is a related, separate task if needed |
What you are seeing
- The mapped domain not resolving at all, or showing an error
- The mapped domain showing the wrong subsite’s content, or the network’s main site instead
- SSL certificate errors specific to the mapped domain
- The issue possibly starting after a DNS change or a plugin update affecting domain mapping
Common causes
- DNS for the mapped domain not correctly pointed at the network’s hosting
- The domain mapping plugin or configuration not correctly associating the domain with the intended subsite
- An SSL certificate not covering the mapped domain, despite covering the network’s primary domain
- A caching issue serving a stale, incorrect association between the domain and subsite
- DNS pointed correctly at the hosting IP, but the server’s own virtual host configuration not recognising the mapped domain as belonging to this installation
What we do
- Verify DNS for the mapped domain points correctly at your hosting
- Check the domain mapping configuration’s association with the intended subsite
- Correct the mapping where it’s misconfigured
- Verify SSL certificate coverage for the mapped domain
- Test that the domain resolves to the correct subsite consistently
- Clear any relevant caching that might be serving a stale association
What is included
- The domain mapping issue identified and corrected
- Verified correct DNS pointing
- Confirmed SSL certificate coverage for the mapped domain
- Tested, consistent resolution to the correct subsite
Not included
- Setting up domain mapping for a subsite that doesn’t have any mapping configured yet in the first place — still covered as part of this fix if that’s genuinely your situation, just noting the scope
- Broader network configuration issues unrelated to this specific domain mapping
- SSL certificate installation as a larger, separate task if none exists yet for the mapped domain
- Ongoing management as you add more mapped domains
Questions about this fix
Why would a mapped domain need its own separate SSL certificate?
A certificate covering your network's primary domain doesn't automatically extend to a completely separate, custom domain mapped to a subsite — that domain needs its own valid certificate for HTTPS to work correctly on it specifically.
Could this be a DNS issue rather than a WordPress configuration issue?
Very possibly, and it's the first thing worth checking, since a domain mapping configured perfectly correctly on the WordPress side still won't work if the domain's DNS isn't actually pointed at your hosting.
Will fixing this affect the network's primary domain or other subsites?
No, this is specific to the one mapped domain and its associated subsite — other subsites and the network's primary domain shouldn't be affected.
What if the mapping shows the wrong subsite entirely, not just an error?
That points at a configuration-level association problem rather than a DNS issue, since DNS being wrong would typically produce an error or the wrong destination server entirely rather than successfully reaching your network but resolving to the wrong subsite within it.
Is domain mapping something that needs ongoing attention, or is it set-and-forget once correct?
Once correctly configured, it's generally stable, though a DNS change, an SSL renewal, or a plugin update affecting mapping could each introduce a new issue worth checking for if something changes.
Related fixes
If this is the second time this year
A bad update breaking the site is a symptom of updates not being tested first. Care plans run every update on a staging clone before it reaches your live site, which is the actual fix for this happening again.
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