4xx Client Error
Use 451 when a legal demand prevents the resource from being provided.
GET /articles/restricted-news451 Unavailable For Legal Reasons with Link: <https://example.com/legal>; rel="blocked-by"The server distinguishes a legal restriction from generic permissions or missing content.
Your request doesn't make sense or has mistakes in it. Check what you're sending and try again.
You need to prove who you are before you can access this. Please log in or provide valid credentials.
You need to pay for this service before you can use it. Please complete payment first.
I know who you are, but you're not allowed to do this. You don't have permission for this action.
The thing you're looking for doesn't exist here. It's like knocking on a door and nobody's home.
You found the right place, but you're trying to do something that's not allowed here. Try a different action.
I can't give you the data in the format you want. I have the data, but not in XML/JSON/etc. that you asked for.
You need to authenticate with the proxy server first before it will forward your request to the destination.
You took too long to send your request. The server got tired of waiting and gave up.
There's a conflict - what you're trying to do clashes with something that already exists or the current state.
This used to exist here, but it's been permanently removed and won't be coming back.
You're trying to send me something, but you didn't tell me how big it is. I need to know the size before I can accept it.
You said 'only do this if that thing is true', but that thing turned out to be false, so I didn't do anything.
The file or data you're trying to send is too big for me to handle. Please make it smaller.
The web address (URL) you're using is too long for me to handle. Please make it shorter or use a different method.
I don't understand the format of data you sent me. Please send it as JSON, XML, or another format I support.
You asked for a specific part of a file (like pages 50-60), but the file only has 10 pages. I can't give you what doesn't exist.
You told me to expect something specific to happen, but I can't make that happen the way you want.
I'm a teapot, not a coffee maker! This is an April Fools' joke code - don't use it in real APIs.
You sent your request to the wrong server. It's like calling the wrong phone number - the person who answered can't help you.
Your request looks right, but the data doesn't make sense according to our business rules. Fix the data and try again.
WebDAVThis file is currently being edited by someone else and they've locked it. You'll have to wait until they're done or unlock it.
WebDAVI couldn't do what you asked because something else you wanted me to do first didn't work out. It's like a domino effect - one failure caused this one.
WebDAVYou're trying to do something too early in the connection process. It's like trying to order food before the restaurant is fully open.
You need to upgrade to a newer or different protocol to access this. It's like needing to update your app to continue using it.
You're trying to change something, but you need to tell me what you expect it to look like first, so we don't accidentally overwrite someone else's changes.
Slow down! You're making too many requests too quickly. Wait a bit and try again later.
Your request headers (the extra information like cookies) are too big for me to handle. Clean up your cookies or make the headers smaller.