How To Fix 400 Bad Request Error

Last Update: March 30, 2019

Just a real quick one today. I read a blog or question yesterday in regard to a member having the same problem as I was and how to fix 400 bad request error which was occurring on our sites.

I can't for the life of me find the question again to respond on it but I wanted to say a huge thank you to Marion Black for her suggestion on that post and share with you what worked for me.

Edit: Thanks again to Marion for providing the link to the original blog from Gordon - check it out here:

I run Thrive on my sites but there was another member who wasn't and was having the same bad request error, so it's not just Thrive and seems like it can be any theme.

After following Marion's suggestion I started disabling and removing plugins to see what didn't play well with my theme and site architecture.

As it turns out I believe it is a clash between the Classic Editor plugin and some themes.

After removing Classic Editor yesterday I have had no more bad error requests on either of the two sites. My third site which I had not downloaded Classic Editor on never had the bad request errors occurring.

So once again thank you Marion for your speedy suggestion, it seems to have fixed my problem, and hopefully others who have this same error may find this blog and can try this fix for themselves.

Edit: Well after a few days the bad request error is back on my MMO niche, but doesn't seem to be affecting the niche site. So this isn't the be all and end all fix I was hoping.

Back to the drawing board with Site Support!

Edit #2: Thanks to Gosa I have now banished the bad request and have access to my site. Try this: click on the lock in the URL that brings up the bad request, clear cookies and bad request disappears. How simpe is that!! Give it a try guys and see how you go.

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Barney44 Premium
The actual things you experienced as your tried removing plugin might be an interesting topic for a length post. Being able to understand what each plugin does with regards to all the others to me is intriguing.

Thanks Heidi for sharing.

HeidiY Premium
It was only the Classic Editor I actually remove on both sites, and while I was going I disabled WP Clone but didn't actually delete it as I do use it occassionally.

Most of my other plugins are part of the Thrive Architecture on both these sites.

The MMO site but I run Sumo, Pretty Links, GDPR Cookie Consent & Blog2Social.

I do run a heap of others on my niche site (hangover from before I upgraded) and I didn't disable or remove any of those. I run Sumo, Blog2Social, WP Product Review, GDPR Cookie Consent, Shortcodes Ultimate, Tablepress, and probably others LOL. I really do need to do a clean up of that site.

Actually pretty boring as nothing happened except the bad request error has not occurred since.
CandP Premium
Good to know, thanks Heidi.
Colette and Philip
FKelso Premium
Good one -- glad you found out.
SaraStorey Premium
That's good to know, Thank you!
RuthlynB Premium
I am so glad you found the solutions to your problem and I do love Marion Black she is my go-to person when I have a problem.
HeidiY Premium
She is an absolute gem Ruthlyn.

I have lost count of the times Marion has helped me, she is a wealth of knowledge and we are very fortunate to have her that is for sure.