Join the AMA (Ask Me Anything) with the Firefox leadership team to celebrate Firefox 20th anniversary and discuss Firefox’s future on Mozilla Connect. Mark your calendar on Thursday, November 14, 18:00 - 20:00 UTC!

This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Bad Request Your browser sent a request that this server could not understand

  • 9 replies
  • 63 have this problem
  • 1 view
  • Last reply by zante

more options

Bad Request

Your browser sent a request that this server could not understand.

I get this message every time I try to upload a picture anywhere in the internet. I have cleared cookies, I have dumped my firefox account, I have cleared my cache, I have removed all history, I have re-installed firefox. Still getting this issue and 've been looking for solution for the last 3 hours and no luck

'''Bad Request Your browser sent a request that this server could not understand.''' I get this message every time I try to upload a picture anywhere in the internet. I have cleared cookies, I have dumped my firefox account, I have cleared my cache, I have removed all history, I have re-installed firefox. Still getting this issue and 've been looking for solution for the last 3 hours and no luck

Chosen solution

If clearing the cookies doesn't help then it is possible that the file cookies.sqlite that stores the cookies is corrupted.
Rename (or delete) cookies.sqlite (cookies.sqlite.old) and delete other present cookie files like cookies.sqlite-journal in the Firefox Profile Folder in case the file cookies.sqlite got corrupted.


Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance/Themes).

Read this answer in context 👍 2

All Replies (9)

more options

That issue can be caused by corrupted cookies.

Clear the cache and the cookies from sites that cause problems.

"Clear the Cache":

  • Tools > Options > Advanced > Network > Offline Storage (Cache): "Clear Now"

"Remove Cookies" from sites causing problems:

  • Tools > Options > Privacy > Cookies: "Show Cookies"
more options

As I said I've cleared cache and removed cookies. Anyways I did it again and no luck, still the same error:

Bad Request

Your browser sent a request that this server could not understand. Apache/2.2.16 (Debian) Server at ylilauta.fi Port 80

It's not just ylilauta.fi, any other site does this as well

more options

Chosen Solution

If clearing the cookies doesn't help then it is possible that the file cookies.sqlite that stores the cookies is corrupted.
Rename (or delete) cookies.sqlite (cookies.sqlite.old) and delete other present cookie files like cookies.sqlite-journal in the Firefox Profile Folder in case the file cookies.sqlite got corrupted.


Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance/Themes).

more options

Okay, so I tried deleting cookies.sqlite. Didn't work out. Then I tried safe mode, and it did work. Weird because even after re-installing it did not work without all the addons. Anyways, now I need to find out which of the addons is conflicting with uploading, any idea how I could identify the one that is causing problems?

more options

Oh well, I cleared out the list and only left the necessities. Thanks for the support, everything seems to be working out now

more options

This worked for me also. A Firefox add-on ( not sure which yet) was preventing an extension from being installed into Joomla

more options

Hi, I had a similar problem uploading a file. I followed your suggestions and I found this plug-in: Microsoft DRM 9.0.0.4503 Network Object After after disabling that plug-in, it works for me

more options

Worked for me as well, I had an issue where i was being blocked from viewing only 1of 4 php apps(not wp plugins), on my wordpress website. The website was also viewable with no errors. I only removed the cookies for that domain and that was enough to fix it thanks!

Modified by dwarbe

more options

Check your permalinks of your web site: make sure are configured correctly; and/or reconfigure them. If you are using "custom permalinks" consult with Wordpress.org how to use custom permalinks.