How to Fix the “Updating failed. The response is not a valid JSON response” Error in WordPress
The Complete Guide to Fixing WordPress JSON Response Errors – You’re about to publish that perfect blog post.
One more click.
Just save the changes and you’re done.
Then WordPress hits you with it: “Updating failed.
The response is not a valid JSON response.”
Your heart sinks.
What did you do wrong?
Nothing, probably.
This error doesn’t care about your innocence.
It shows up uninvited, ruins your workflow, and leaves you staring at the screen wondering what fresh hell this is.
Here’s what’s actually happening.
WordPress uses something called the REST API to communicate between your editor and your server.
Think of it like a telephone line.
You speak into one end, your words travel through the wire, and someone hears you on the other end.
The JSON response is the confirmation that your message got through clearly.
When that confirmation comes back garbled, or doesn’t come back at all, WordPress panics and refuses to save your work.
The good news?
This error has a short list of usual suspects.
The bad news?
You’ll need to check them one by one until you find the culprit.
No shortcuts here, just steady detective work.
Let’s fix this thing.
Refresh Your Permalink Structure First
This sounds too simple to work.
You’re probably rolling your eyes right now.
But permalink problems cause this error more often than anything else, and the fix takes exactly ten seconds.
Your permalinks are the URL structure WordPress uses to organize your content.
They’re also the foundation for the REST API to function properly.
When those permalinks get corrupted or confused, the entire communication system breaks down.
WordPress sends a request, the request gets lost in broken routing rules, and you get that error message.
How to Regenerate Your Permalinks
Navigate to Settings → Permalinks in your WordPress dashboard.
Don’t change any settings.
Don’t touch the radio buttons.
Just scroll down to the bottom and click Save Changes.
That’s the whole process.
This forces WordPress to rebuild its rewrite rules from scratch.
Those rules tell your server how to handle different types of requests, including the REST API calls that save your content.
By clicking save, you’re essentially telling WordPress to clean house and start fresh.
Try updating your post now.
If the error disappears, you’re done.
If it’s still glaring at you, keep reading, because we’re just getting started.
Deactivate Your Plugins Systematically
Plugins extend WordPress functionality, which is beautiful when they work and catastrophic when they don’t.
Security plugins are the worst offenders here.
They see the REST API making requests and think it’s an attack, blocking legitimate traffic from your own editor.
The only way to know for sure which plugin is causing the problem is to deactivate them all and test.
Yes, all of them.
The one you installed yesterday, the one you’ve trusted for years, even the one that seems completely unrelated to saving posts.
The Deactivation Process
Go to Plugins → Installed Plugins in your dashboard.
Click the checkbox at the very top of the plugin list to select everything.
Choose Deactivate from the bulk actions dropdown and hit Apply.
Your site will survive this.
You’re not deleting anything, just temporarily turning things off.
Now try updating your post again.
If it works, one of those plugins was the problem.
Reactivate them one at a time, testing after each reactivation, until the error returns.
When it does, you’ve found your culprit.
Common Plugin Troublemakers
Security plugins lead the pack here.
Wordfence, iThemes Security, All In One WP Security, they all have settings that can block REST API access.
Check their settings for options related to “REST API” or “XML-RPC” and make sure they’re not blocking everything.
Caching plugins cause problems too.
They serve old versions of your site, including outdated API responses, and WordPress gets confused.
Page builders sometimes inject code that interferes with JSON responses.
Even anti-spam plugins can get overzealous and block legitimate requests.
Once you identify the problem plugin, you have three choices.
Configure it properly so it stops blocking the REST API.
Find a different plugin that does the same job without breaking your editor.
Or delete it entirely and live without that functionality.
Switch to a Default Theme Temporarily
Your theme controls how your site looks, but it also runs code that can interfere with core WordPress functions.
Poorly coded themes, especially those downloaded from questionable sources, sometimes break the REST API without meaning to.
Testing this is straightforward.
Go to Appearance → Themes, activate one of the default WordPress themes like Twenty Twenty-Four or Twenty Twenty-Three, then try updating your post.
If the error vanishes, your theme was the problem.
What to Do If Your Theme Is Broken
You have a few options here, none of them great.
You can contact the theme developer and report the bug, assuming they’re still in business and responsive.
You can hire a developer to fix the broken code.
Or you can switch to a different theme entirely and rebuild your site’s appearance from scratch.
This is why choosing a quality theme from the start matters.
Free themes from shady sites might look gorgeous, but they’re often coded by people who don’t understand how WordPress actually works.
Premium themes from reputable marketplaces usually avoid these problems, and when they don’t, they have support teams to help fix them.
Rebuild Your .htaccess File
The .htaccess file sits in your WordPress root directory and controls how your server handles incoming requests.
It’s a powerful file.
It’s also fragile.
Plugins modify it, server configurations change it, and sometimes it just gets corrupted for no reason anyone can explain.
When .htaccess breaks, it can block the REST API completely.
The requests come in, hit the corrupted rules in that file, and die before they ever reach WordPress.
Your editor sends a save request and gets nothing back, triggering the JSON error.
How to Delete and Regenerate .htaccess
Connect to your site using FTP or your hosting control panel’s file manager.
Look for the .htaccess file in your root directory, the same folder that contains wp-config.php and wp-content.
Download a backup copy to your computer, just in case you need to restore it.
Then delete the file.
Just remove it completely.
Now go back to your WordPress dashboard, navigate to Settings → Permalinks, and click Save Changes without changing anything.
WordPress will automatically generate a fresh, uncorrupted .htaccess file with all the correct rules.
Test your update again.
If you can’t find the .htaccess file, it might be hidden.
Most FTP programs and file managers have a setting to show hidden files.
Enable that and look again.
The file starts with a period, which makes it hidden by default on most systems.
Verify Your Site URL Settings Match
WordPress needs to know where it lives on the internet.
It stores this information in two fields: WordPress Address and Site Address.
When these don’t match, when one says HTTP and the other says HTTPS, when one includes www and the other doesn’t, WordPress gets confused and the REST API breaks.
This seems minor, but it creates a fundamental identity crisis for your site.
The editor sends a request to one address, the server responds from a different address, and WordPress sees that mismatch and rejects the entire transaction.
How to Check and Fix Your URLs
Navigate to Settings → General in your dashboard.
Look at the WordPress Address (URL) and Site Address (URL) fields.
They should be identical.
Same protocol, same domain, same everything.
If one says http://yoursite.com and the other says https://yoursite.com, fix them.
If one includes www and the other doesn’t, fix them.
Make them match exactly, save the changes, and test your update again.
A word of caution here: changing these URLs can lock you out of your dashboard if you do it wrong.
Make sure you know the correct URL for your site before you start typing.
If you’re unsure, contact your hosting provider and ask them what your site’s proper URL should be.
Test If Your REST API Is Actually Working
Some hosting companies disable the REST API entirely.
Some security configurations block it.
Some server setups break it without anyone realizing what happened.
Before you spend hours troubleshooting, verify that your REST API is actually functional.
Type this into your browser’s address bar, replacing yoursite.com with your actual domain: yoursite.com/wp-json/wp/v2/posts
If you see a page full of JSON data, your REST API works.
If you see an error message, a blank page, or some kind of security warning, your REST API is blocked or disabled.
How to Enable a Disabled REST API
If your REST API is blocked, you need to find out who blocked it and why.
Check your security plugin settings first.
Look for options related to REST API access and make sure they’re not set to block everything.
If a plugin isn’t the problem, your hosting company might have disabled the REST API at the server level.
Contact their support team and explain what’s happening.
They can either enable it for you or explain why it’s disabled and what alternatives you have.
In extreme cases, you can try adding code to your theme’s functions.php file to force the REST API to work, but this is a band-aid solution.
If your host has disabled the REST API and won’t enable it, you probably need a better host.
Clear Your Browser Cache and Try a Different Browser
Sometimes the problem isn’t WordPress at all.
It’s your browser, stubbornly holding onto outdated data, showing you old error messages even though the server is trying to tell you everything’s fine now.
Browsers cache everything to make websites load faster.
Normally this is helpful.
When you’re troubleshooting, it’s infuriating.
Your browser shows you the cached version of the error while the actual server is working perfectly, and you waste hours chasing a problem that doesn’t exist anymore.
The Quick Browser Test
Open an incognito or private browsing window and try updating your post there.
If it works, your regular browser cache was the problem.
Clear your cache and cookies completely, restart the browser, and try again in a normal window.
Better yet, try a completely different browser.
If you normally use Chrome, try Firefox or Safari.
If it works in a different browser, you know the problem is browser-specific, not WordPress-specific.
This fix feels stupid.
It feels like something a tech support person suggests when they can’t figure out the real problem.
But you’d be shocked how often it actually works.
When Nothing Else Works
You’ve tried everything on this list.
You’ve reset permalinks, deactivated plugins, switched themes, rebuilt .htaccess, verified your URLs, tested the REST API, and cleared your cache.
The error is still there, mocking you.
At this point, the problem is probably something specific to your hosting environment or a deeper corruption in your WordPress installation.
Contact your hosting company’s support team and explain what you’ve already tried.
They have access to server logs that can reveal what’s actually failing.
If your host can’t help, consider restoring from a backup to a point before the error started appearing.
If you don’t have backups, well, this is an excellent time to start making them.
The nuclear option is reinstalling WordPress core files.
This won’t delete your content or settings, but it will replace all the core WordPress files with fresh copies.
Sometimes a corrupted core file causes this error, and reinstalling fixes it.
The Real Problem Behind the Error
This error exists because modern WordPress is complicated.
The block editor, the REST API, the JavaScript-heavy interface, they all work beautifully when everything is configured correctly.
But they’re fragile.
One broken plugin, one misconfigured setting, one corrupted file, and the whole system breaks down.
The error message itself is useless.
“The response is not a valid JSON response” tells you nothing about what actually went wrong.
It’s like your car refusing to start and the only message being “the engine did not respond correctly.” Thanks for nothing.
But that’s why you work through the list methodically.
Permalinks first, plugins second, theme third, .htaccess fourth, URLs fifth, REST API sixth, browser cache seventh.
One of these will fix it.
Almost always.
Don’t skip steps because you think you know better.
Don’t assume your favorite plugin couldn’t possibly be the problem.
Don’t convince yourself the error will fix itself if you just wait long enough.
It won’t.
Start at the top, work down, test after each change, and you’ll find the problem.
Then fix it, save your work, and get back to creating content instead of fighting with error messages that sound like they were written by a malfunctioning robot.
