Full Site Editing templates are themselves just specially-structured block content, stored and validated the same way a post’s content is, which means the same kind of validation mismatch that can affect a single block can also affect an entire template — except when it happens at the template level, the impact is a broken header, footer, or archive layout across every page using it, not just one piece of content. That wider blast radius is exactly what makes a template-level error more urgent to resolve than an equivalent issue in a single post, since visitors encounter the same broken element on every page that relies on the affected template, not just one.
Check whether the error is template-wide or one block
Read-only. Open the Site Editor and check whether the error appears the moment the template loads, or only when you interact with one specific block or pattern inside it.
An error tied to one specific block within the template points at a narrower cause than the entire template being broken, and it’s a useful distinction to have ready before ordering.
It’s also worth checking whether the error appeared right after a theme or plugin update, since that timing is often the single clearest clue toward what actually changed the template’s expected structure.
Full Site Editing template errors
A Full Site Editing template is throwing an error or failing to render. We isolate whether it's the template, a pattern, or a theme.json conflict.
- Full backup taken before we start
- If we can’t fix it, you get your money back
- We never ask for your own password
This or something else?
| A Full Site Editing template shows an error or fails to render properly | This fix covers it |
| A single block within regular post content shows a validation error, not a template | Custom block validation errors, a different but related fix |
| theme.json settings and another style source are in conflict, not a template error | Global styles & theme.json conflict fix, a different fix |
| The block editor itself won’t load at all for any content | Block editor not loading – diagnosis, a different fix |
| The theme doesn’t use Full Site Editing or block templates at all | This fix likely doesn’t apply; a different diagnosis fits better |
What you are seeing
- An error or warning shown when opening a specific template in the Site Editor
- A template rendering incorrectly on the live site, even if the editor shows no obvious error
- The issue affecting every page using the template, such as every archive or single post
- The problem appearing after a theme update, plugin update, or template edit
- A specific block or pattern within the template behaving differently than expected
Common causes
- A theme update replacing its default templates, leaving a customised one out of step with the new template hierarchy
- A template part — the header or footer — edited independently of the templates that include it, so the two now disagree
- A plugin registering its own template for a custom post type, conflicting with one already customised in the Site Editor
- The template calling a block setting removed from theme.json, so a style reference it depends on no longer resolves
- A classic PHP template and a block-based version of the same template both existing at once, with WordPress picking between them unpredictably
What we do
- Open the specific template in the Site Editor and confirm exactly which page types it actually governs
- Check whether the template itself, or a template part like the header or footer, is the real source of the error
- Repair the template’s structure to match the current theme’s template hierarchy
- Confirm theme.json’s own settings still resolve correctly against the repaired template
- Confirm every page type using the template renders correctly, not just the one you noticed
- Check the theme’s other templates for the same latent structural issue
What is included
- The specific template issue identified and repaired
- Verification across every page type the template affects
- A check for the same issue in other templates
- The pre-fix backup, kept for 30 days
Not included
- Redesigning the template beyond restoring it to a valid, working state
- Fixing a third-party block plugin’s own underlying bugs
- Resolving a separate theme.json and global-style conflict, which is a distinct fix
- Ongoing monitoring for future theme updates affecting templates
Questions about this fix
Does the fix touch my header and footer separately, or just the one template?
Just the specific template, and any template part it actually calls — a header or footer used elsewhere on the site is only touched if it's genuinely part of what's broken.
If I just revert to my theme's original template, does that fix it?
Sometimes, but only if you've never customised it — reverting discards any changes you've made in the Site Editor, which usually isn't what you actually want, so we fix the structural problem instead of resetting and hoping.
Could a plugin update really break a template I haven't touched?
Yes, if the plugin changes how a block it provides is structured or rendered, any template using that block can be affected even though nothing about the template itself was directly edited.
Is this the same as the theme.json conflict issue?
Related but distinct — that's specifically about competing global style sources; this is about the template's own structural validity, though the two can occasionally intersect.
Will this happen again after the next theme update?
Possibly, if a future update changes template structure again, though understanding the specific cause this time makes it faster to recognise and fix if it recurs.
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.
Your access, your rules
Create a separate admin account for us and delete it when we are done. For anything else, we get in touch and agree a method — never a form field on this site, never by reply to an email.
We back up first, always
Before anything is touched we take a full backup and keep it for 30 days. If a fix goes wrong, we put the site back exactly as it was.
If it is not what you bought
If the problem turns out smaller than what you ordered, we refund the difference. If it is bigger, we stop and send a quote before doing any extra work.
If we cannot fix it
You get back what we received. Diagnosis is on us — you only pay when the problem is actually solved. The payment processor takes its fee before the money reaches us, so we never hold it and it is not ours to return. That is true here as everywhere else.
If it comes back
Reply within seven days of delivery and we put it back on the bench at no cost. The fix is not finished until it holds.
What we are responsible for
If something goes wrong with a fix, our responsibility is limited to what you paid for it. We take a full backup first so mistakes can be undone, and we tell you before doing anything outside what you bought.