<s>
This	O
is	O
a	O
list	O
of	O
Hypertext	B-Protocol
Transfer	I-Protocol
Protocol	I-Protocol
(	O
HTTP	B-Protocol
)	O
response	O
status	O
codes	O
.	O
</s>
<s>
Status	O
codes	O
are	O
issued	O
by	O
a	O
server	B-Application
in	O
response	O
to	O
a	O
client	B-Protocol
's	I-Protocol
request	I-Protocol
made	O
to	O
the	O
server	B-Application
.	O
</s>
<s>
It	O
includes	O
codes	O
from	O
IETF	O
Request	O
for	O
Comments	O
(	O
RFCs	O
)	O
,	O
other	O
specifications	O
,	O
and	O
some	O
additional	O
codes	O
used	O
in	O
some	O
common	O
applications	O
of	O
the	O
HTTP	B-Protocol
.	I-Protocol
</s>
<s>
Unless	O
otherwise	O
stated	O
,	O
the	O
status	O
code	O
is	O
part	O
of	O
the	O
HTTP	B-Protocol
standard	O
(	O
)	O
.	O
</s>
<s>
The	O
Internet	O
Assigned	O
Numbers	O
Authority	O
(	O
IANA	O
)	O
maintains	O
the	O
official	O
registry	O
of	O
HTTP	B-Protocol
status	O
codes	O
.	O
</s>
<s>
All	O
HTTP	B-Protocol
response	O
status	O
codes	O
are	O
separated	O
into	O
five	O
classes	O
or	O
categories	O
.	O
</s>
<s>
As	O
the	O
HTTP/1.0	B-Protocol
standard	O
did	O
not	O
define	O
any	O
1xx	O
status	O
codes	O
,	O
servers	O
send	O
a	O
1xx	O
response	O
to	O
an	O
HTTP/1.0	B-Protocol
compliant	O
client	O
except	O
under	O
experimental	O
conditions	O
.	O
</s>
<s>
The	O
server	B-Application
has	O
received	O
the	O
request	O
headers	O
and	O
the	O
client	O
should	O
proceed	O
to	O
send	O
the	O
request	O
body	O
(	O
in	O
the	O
case	O
of	O
a	O
request	O
for	O
which	O
a	O
body	O
needs	O
to	O
be	O
sent	O
;	O
for	O
example	O
,	O
a	O
POST	B-Protocol
request	I-Protocol
)	O
.	O
</s>
<s>
Sending	O
a	O
large	O
request	O
body	O
to	O
a	O
server	B-Application
after	O
a	O
request	O
has	O
been	O
rejected	O
for	O
inappropriate	O
headers	O
would	O
be	O
inefficient	O
.	O
</s>
<s>
To	O
have	O
a	O
server	B-Application
check	O
the	O
request	O
's	O
headers	O
,	O
a	O
client	O
must	O
send	O
Expect	O
:	O
100-continue	O
as	O
a	O
header	O
in	O
its	O
initial	O
request	O
and	O
receive	O
a	O
100	O
Continue	O
status	O
code	O
in	O
response	O
before	O
sending	O
the	O
body	O
.	O
</s>
<s>
The	O
response	O
417	O
Expectation	O
Failed	O
indicates	O
that	O
the	O
request	O
should	O
be	O
repeated	O
without	O
the	O
Expect	O
header	O
as	O
it	O
indicates	O
that	O
the	O
server	B-Application
does	O
not	O
support	O
expectations	O
(	O
this	O
is	O
the	O
case	O
,	O
for	O
example	O
,	O
of	O
HTTP/1.0	B-Protocol
servers	O
)	O
.	O
</s>
<s>
The	O
requester	O
has	O
asked	O
the	O
server	B-Application
to	O
switch	O
protocols	O
and	O
the	O
server	B-Application
has	O
agreed	O
to	O
do	O
so	O
.	O
</s>
<s>
A	O
WebDAV	B-Protocol
request	O
may	O
contain	O
many	O
sub-requests	O
involving	O
file	O
operations	O
,	O
requiring	O
a	O
long	O
time	O
to	O
complete	O
the	O
request	O
.	O
</s>
<s>
This	O
code	O
indicates	O
that	O
the	O
server	B-Application
has	O
received	O
and	O
is	O
processing	O
the	O
request	O
,	O
but	O
no	O
response	O
is	O
available	O
yet	O
.	O
</s>
<s>
Used	O
to	O
return	O
some	O
response	O
headers	O
before	O
final	O
HTTP	B-Protocol
message	O
.	O
</s>
<s>
Standard	O
response	O
for	O
successful	O
HTTP	B-Protocol
requests	I-Protocol
.	O
</s>
<s>
In	O
a	O
POST	B-Protocol
request	I-Protocol
,	O
the	O
response	O
will	O
contain	O
an	O
entity	O
describing	O
or	O
containing	O
the	O
result	O
of	O
the	O
action	O
.	O
</s>
<s>
The	O
server	B-Application
is	O
a	O
transforming	O
proxy	B-Application
(	O
e.g.	O
</s>
<s>
The	O
server	B-Application
successfully	O
processed	O
the	O
request	O
,	O
and	O
is	O
not	O
returning	O
any	O
content	O
.	O
</s>
<s>
The	O
server	B-Application
successfully	O
processed	O
the	O
request	O
,	O
asks	O
that	O
the	O
requester	O
reset	O
its	O
document	O
view	O
,	O
and	O
is	O
not	O
returning	O
any	O
content	O
.	O
</s>
<s>
The	O
server	B-Application
is	O
delivering	O
only	O
part	O
of	O
the	O
resource	O
(	O
byte	B-Protocol
serving	I-Protocol
)	O
due	O
to	O
a	O
range	O
header	O
sent	O
by	O
the	O
client	O
.	O
</s>
<s>
The	O
range	O
header	O
is	O
used	O
by	O
HTTP	B-Protocol
clients	O
to	O
enable	O
resuming	O
of	O
interrupted	O
downloads	O
,	O
or	O
split	O
a	O
download	O
into	O
multiple	O
simultaneous	O
streams	O
.	O
</s>
<s>
The	O
message	O
body	O
that	O
follows	O
is	O
by	O
default	O
an	O
XML	B-Protocol
message	O
and	O
can	O
contain	O
a	O
number	O
of	O
separate	O
response	O
codes	O
,	O
depending	O
on	O
how	O
many	O
sub-requests	O
were	O
made	O
.	O
</s>
<s>
The	O
server	B-Application
has	O
fulfilled	O
a	O
request	O
for	O
the	O
resource	O
,	O
and	O
the	O
response	O
is	O
a	O
representation	O
of	O
the	O
result	O
of	O
one	O
or	O
more	O
instance-manipulations	O
applied	O
to	O
the	O
current	O
instance	O
.	O
</s>
<s>
Indicates	O
multiple	O
options	O
for	O
the	O
resource	O
from	O
which	O
the	O
client	O
may	O
choose	O
(	O
via	O
agent-driven	O
content	B-Protocol
negotiation	I-Protocol
)	O
.	O
</s>
<s>
For	O
example	O
,	O
this	O
code	O
could	O
be	O
used	O
to	O
present	O
multiple	O
video	O
format	O
options	O
,	O
to	O
list	O
files	O
with	O
different	O
filename	O
extensions	O
,	O
or	O
to	O
suggest	O
word-sense	B-General_Concept
disambiguation	I-General_Concept
.	O
</s>
<s>
This	O
and	O
all	O
future	O
requests	O
should	O
be	O
directed	O
to	O
the	O
given	O
URI	B-Protocol
.	O
</s>
<s>
The	O
HTTP/1.0	B-Protocol
specification	O
(	O
RFC	O
1945	O
)	O
required	O
the	O
client	O
to	O
perform	O
a	O
temporary	O
redirect	O
with	O
the	O
same	O
method	O
(	O
the	O
original	O
describing	O
phrase	O
was	O
"	O
Moved	O
Temporarily	O
"	O
)	O
,	O
but	O
popular	O
browsers	O
implemented	O
302	B-Protocol
redirects	I-Protocol
by	O
changing	O
the	O
method	O
to	O
GET	O
.	O
</s>
<s>
Therefore	O
,	O
HTTP/1.1	B-Protocol
added	O
status	O
codes	O
303	O
and	O
307	O
to	O
distinguish	O
between	O
the	O
two	O
behaviours	O
.	O
</s>
<s>
The	O
response	O
to	O
the	O
request	O
can	O
be	O
found	O
under	O
another	O
URI	B-Protocol
using	O
the	O
GET	O
method	O
.	O
</s>
<s>
When	O
received	O
in	O
response	O
to	O
a	O
POST	B-Protocol
(	O
or	O
PUT/DELETE	O
)	O
,	O
the	O
client	O
should	O
presume	O
that	O
the	O
server	B-Application
has	O
received	O
the	O
data	O
and	O
should	O
issue	O
a	O
new	O
GET	O
request	O
to	O
the	O
given	O
URI	B-Protocol
.	O
</s>
<s>
The	O
requested	O
resource	O
is	O
available	O
only	O
through	O
a	O
proxy	B-Application
,	O
the	O
address	O
for	O
which	O
is	O
provided	O
in	O
the	O
response	O
.	O
</s>
<s>
For	O
security	O
reasons	O
,	O
many	O
HTTP	B-Protocol
clients	O
(	O
such	O
as	O
Mozilla	B-Application
Firefox	I-Application
and	O
Internet	B-Application
Explorer	I-Application
)	O
do	O
not	O
obey	O
this	O
status	O
code	O
.	O
</s>
<s>
Originally	O
meant	O
"	O
Subsequent	O
requests	O
should	O
use	O
the	O
specified	O
proxy.	O
"	O
</s>
<s>
In	O
this	O
case	O
,	O
the	O
request	O
should	O
be	O
repeated	O
with	O
another	O
URI	B-Protocol
;	O
however	O
,	O
future	O
requests	O
should	O
still	O
use	O
the	O
original	O
URI	B-Protocol
.	O
</s>
<s>
For	O
example	O
,	O
a	O
POST	B-Protocol
request	I-Protocol
should	O
be	O
repeated	O
using	O
another	O
POST	B-Protocol
request	I-Protocol
.	O
</s>
<s>
This	O
and	O
all	O
future	O
requests	O
should	O
be	O
directed	O
to	O
the	O
given	O
URI	B-Protocol
.	O
</s>
<s>
Except	O
when	O
responding	O
to	O
a	O
HEAD	O
request	O
,	O
the	O
server	B-Application
include	O
an	O
entity	O
containing	O
an	O
explanation	O
of	O
the	O
error	O
situation	O
,	O
and	O
whether	O
it	O
is	O
a	O
temporary	O
or	O
permanent	O
condition	O
.	O
</s>
<s>
The	O
server	B-Application
cannot	O
or	O
will	O
not	O
process	O
the	O
request	O
due	O
to	O
an	O
apparent	O
client	O
error	O
(	O
e.g.	O
,	O
malformed	O
request	O
syntax	O
,	O
size	O
too	O
large	O
,	O
invalid	O
request	O
message	O
framing	O
,	O
or	O
deceptive	O
request	O
routing	O
)	O
.	O
</s>
<s>
Similar	O
to	O
403	B-Protocol
Forbidden	I-Protocol
,	O
but	O
specifically	O
for	O
use	O
when	O
authentication	O
is	O
required	O
and	O
has	O
failed	O
or	O
has	O
not	O
yet	O
been	O
provided	O
.	O
</s>
<s>
See	O
Basic	B-Protocol
access	I-Protocol
authentication	I-Protocol
and	O
Digest	B-Protocol
access	I-Protocol
authentication	I-Protocol
.	O
</s>
<s>
Some	O
sites	O
incorrectly	O
issue	O
HTTP	B-Protocol
401	O
when	O
an	O
IP	B-Protocol
address	I-Protocol
is	O
banned	O
from	O
the	O
website	O
(	O
usually	O
the	O
website	O
domain	O
)	O
and	O
that	O
specific	O
address	O
is	O
refused	O
permission	O
to	O
access	O
a	O
website	O
.	O
</s>
<s>
The	O
original	O
intention	O
was	O
that	O
this	O
code	O
might	O
be	O
used	O
as	O
part	O
of	O
some	O
form	O
of	O
digital	O
cash	O
or	O
micropayment	O
scheme	O
,	O
as	O
proposed	O
,	O
for	O
example	O
,	O
by	O
GNU	B-Application
Taler	I-Application
,	O
but	O
that	O
has	O
not	O
yet	O
happened	O
,	O
and	O
this	O
code	O
is	O
not	O
widely	O
used	O
.	O
</s>
<s>
Google	B-Application
Developers	I-Application
API	O
uses	O
this	O
status	O
if	O
a	O
particular	O
developer	O
has	O
exceeded	O
the	O
daily	O
limit	O
on	O
requests	O
.	O
</s>
<s>
Stripe	B-Application
uses	O
this	O
code	O
for	O
failed	O
payments	O
where	O
parameters	O
were	O
correct	O
,	O
for	O
example	O
blocked	O
fraudulent	O
payments	O
.	O
</s>
<s>
The	O
request	O
contained	O
valid	O
data	O
and	O
was	O
understood	O
by	O
the	O
server	B-Application
,	O
but	O
the	O
server	B-Application
is	O
refusing	O
action	O
.	O
</s>
<s>
This	O
code	O
is	O
also	O
typically	O
used	O
if	O
the	O
request	O
provided	O
authentication	O
by	O
answering	O
the	O
WWW-Authenticate	O
header	O
field	O
challenge	O
,	O
but	O
the	O
server	B-Application
did	O
not	O
accept	O
that	O
authentication	O
.	O
</s>
<s>
A	O
request	O
method	O
is	O
not	O
supported	O
for	O
the	O
requested	O
resource	O
;	O
for	O
example	O
,	O
a	O
GET	O
request	O
on	O
a	O
form	O
that	O
requires	O
data	O
to	O
be	O
presented	O
via	O
POST	B-Protocol
,	O
or	O
a	O
PUT	O
request	O
on	O
a	O
read-only	O
resource	O
.	O
</s>
<s>
See	O
Content	B-Protocol
negotiation	I-Protocol
.	O
</s>
<s>
The	O
client	O
must	O
first	O
authenticate	O
itself	O
with	O
the	O
proxy	B-Application
.	O
</s>
<s>
The	O
server	B-Application
timed	O
out	O
waiting	O
for	O
the	O
request	O
.	O
</s>
<s>
According	O
to	O
HTTP	B-Protocol
specifications	O
:	O
"	O
The	O
client	O
did	O
not	O
produce	O
a	O
request	O
within	O
the	O
time	O
that	O
the	O
server	B-Application
was	O
prepared	O
to	O
wait	O
.	O
</s>
<s>
Indicates	O
that	O
the	O
request	O
could	O
not	O
be	O
processed	O
because	O
of	O
conflict	O
in	O
the	O
current	O
state	O
of	O
the	O
resource	O
,	O
such	O
as	O
an	O
edit	B-Operating_System
conflict	I-Operating_System
between	O
multiple	O
simultaneous	O
updates	O
.	O
</s>
<s>
Most	O
use	O
cases	O
do	O
not	O
require	O
clients	O
and	O
search	O
engines	O
to	O
purge	O
the	O
resource	O
,	O
and	O
a	O
"	O
404	B-Protocol
Not	I-Protocol
Found	I-Protocol
"	O
may	O
be	O
used	O
instead	O
.	O
</s>
<s>
The	O
server	B-Application
does	O
not	O
meet	O
one	O
of	O
the	O
preconditions	O
that	O
the	O
requester	O
put	O
on	O
the	O
request	O
header	O
fields	O
.	O
</s>
<s>
The	O
request	O
is	O
larger	O
than	O
the	O
server	B-Application
is	O
willing	O
or	O
able	O
to	O
process	O
.	O
</s>
<s>
Previously	O
called	O
"	O
Request	O
Entity	O
Too	O
Large	O
"	O
in	O
RFC	B-Protocol
2616	I-Protocol
.	O
</s>
<s>
The	O
URI	B-Protocol
provided	O
was	O
too	O
long	O
for	O
the	O
server	B-Application
to	O
process	O
.	O
</s>
<s>
Often	O
the	O
result	O
of	O
too	O
much	O
data	O
being	O
encoded	O
as	O
a	O
query-string	O
of	O
a	O
GET	O
request	O
,	O
in	O
which	O
case	O
it	O
should	O
be	O
converted	O
to	O
a	O
POST	B-Protocol
request	I-Protocol
.	O
</s>
<s>
Called	O
"	O
Request-URI	O
Too	O
Long	O
"	O
previously	O
in	O
RFC	B-Protocol
2616	I-Protocol
.	O
</s>
<s>
The	O
request	O
entity	O
has	O
a	O
media	B-Application
type	I-Application
which	O
the	O
server	B-Application
or	O
resource	O
does	O
not	O
support	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
client	O
uploads	O
an	O
image	O
as	O
image/svg	B-Application
+xml	I-Application
,	O
but	O
the	O
server	B-Application
requires	O
that	O
images	O
use	O
a	O
different	O
format	O
.	O
</s>
<s>
The	O
client	O
has	O
asked	O
for	O
a	O
portion	O
of	O
the	O
file	O
(	O
byte	B-Protocol
serving	I-Protocol
)	O
,	O
but	O
the	O
server	B-Application
cannot	O
supply	O
that	O
portion	O
.	O
</s>
<s>
Called	O
"	O
Requested	O
Range	O
Not	O
Satisfiable	O
"	O
previously	O
RFC	B-Protocol
2616	I-Protocol
.	O
</s>
<s>
The	O
server	B-Application
cannot	O
meet	O
the	O
requirements	O
of	O
the	O
Expect	O
request-header	O
field	O
.	O
</s>
<s>
This	O
code	O
was	O
defined	O
in	O
1998	O
as	O
one	O
of	O
the	O
traditional	O
IETF	O
April	O
Fools	O
 '	O
jokes	O
,	O
in	O
RFC	B-Protocol
2324	I-Protocol
,	O
Hyper	B-Protocol
Text	I-Protocol
Coffee	I-Protocol
Pot	I-Protocol
Control	I-Protocol
Protocol	I-Protocol
,	O
and	O
is	O
not	O
expected	O
to	O
be	O
implemented	O
by	O
actual	O
HTTP	B-Protocol
servers	O
.	O
</s>
<s>
This	O
HTTP	B-Protocol
status	O
is	O
used	O
as	O
an	O
Easter	O
egg	O
in	O
some	O
websites	O
,	O
such	O
as	O
com	B-Application
's	I-Application
"	O
I	O
'm	O
a	O
teapot	O
"	O
easter	O
egg	O
.	O
</s>
<s>
Sometimes	O
,	O
this	O
status	O
code	O
is	O
also	O
used	O
as	O
a	O
response	O
to	O
a	O
blocked	O
request	O
,	O
instead	O
of	O
the	O
more	O
appropriate	O
403	B-Protocol
Forbidden	I-Protocol
.	O
</s>
<s>
The	O
request	O
was	O
directed	O
at	O
a	O
server	B-Application
that	O
is	O
not	O
able	O
to	O
produce	O
a	O
response	O
(	O
for	O
example	O
because	O
of	O
connection	O
reuse	O
)	O
.	O
</s>
<s>
Indicates	O
that	O
the	O
server	B-Application
is	O
unwilling	O
to	O
risk	O
processing	O
a	O
request	O
that	O
might	O
be	O
replayed	O
.	O
</s>
<s>
The	O
client	O
should	O
switch	O
to	O
a	O
different	O
protocol	O
such	O
as	O
TLS/1.3	B-Protocol
,	O
given	O
in	O
the	O
Upgrade	B-Protocol
header	I-Protocol
field	O
.	O
</s>
<s>
The	O
origin	O
server	B-Application
requires	O
the	O
request	O
to	O
be	O
conditional	O
.	O
</s>
<s>
Intended	O
to	O
prevent	O
the	O
'	O
lost	O
update	O
 '	O
problem	O
,	O
where	O
a	O
client	O
GETs	O
a	O
resource	O
's	O
state	O
,	O
modifies	O
it	O
,	O
and	O
PUTs	O
it	O
back	O
to	O
the	O
server	B-Application
,	O
when	O
meanwhile	O
a	O
third	O
party	O
has	O
modified	O
the	O
state	O
on	O
the	O
server	B-Application
,	O
leading	O
to	O
a	O
conflict	O
.	O
</s>
<s>
The	O
server	B-Application
is	O
unwilling	O
to	O
process	O
the	O
request	O
because	O
either	O
an	O
individual	O
header	O
field	O
,	O
or	O
all	O
the	O
header	O
fields	O
collectively	O
,	O
are	O
too	O
large	O
.	O
</s>
<s>
A	O
server	B-Application
operator	O
has	O
received	O
a	O
legal	O
demand	O
to	O
deny	O
access	O
to	O
a	O
resource	O
or	O
to	O
a	O
set	O
of	O
resources	O
that	O
includes	O
the	O
requested	O
resource	O
.	O
</s>
<s>
The	O
code	O
451	O
was	O
chosen	O
as	O
a	O
reference	O
to	O
the	O
novel	O
Fahrenheit	B-Device
451	I-Device
(	O
see	O
the	O
Acknowledgements	O
in	O
the	O
RFC	O
)	O
.	O
</s>
<s>
The	O
server	B-Application
failed	O
to	O
fulfil	O
a	O
request	O
.	O
</s>
<s>
Response	O
status	O
codes	O
beginning	O
with	O
the	O
digit	O
"	O
5	O
"	O
indicate	O
cases	O
in	O
which	O
the	O
server	B-Application
is	O
aware	O
that	O
it	O
has	O
encountered	O
an	O
error	O
or	O
is	O
otherwise	O
incapable	O
of	O
performing	O
the	O
request	O
.	O
</s>
<s>
Except	O
when	O
responding	O
to	O
a	O
HEAD	O
request	O
,	O
the	O
server	B-Application
include	O
an	O
entity	O
containing	O
an	O
explanation	O
of	O
the	O
error	O
situation	O
,	O
and	O
indicate	O
whether	O
it	O
is	O
a	O
temporary	O
or	O
permanent	O
condition	O
.	O
</s>
<s>
The	O
server	B-Application
either	O
does	O
not	O
recognize	O
the	O
request	O
method	O
,	O
or	O
it	O
lacks	O
the	O
ability	O
to	O
fulfil	O
the	O
request	O
.	O
</s>
<s>
The	O
server	B-Application
was	O
acting	O
as	O
a	O
gateway	B-Application
or	O
proxy	B-Application
and	O
received	O
an	O
invalid	O
response	O
from	O
the	O
upstream	O
server	B-Application
.	O
</s>
<s>
The	O
server	B-Application
cannot	O
handle	O
the	O
request	O
(	O
because	O
it	O
is	O
overloaded	O
or	O
down	O
for	O
maintenance	O
)	O
.	O
</s>
<s>
The	O
server	B-Application
was	O
acting	O
as	O
a	O
gateway	B-Application
or	O
proxy	B-Application
and	O
did	O
not	O
receive	O
a	O
timely	O
response	O
from	O
the	O
upstream	O
server	B-Application
.	O
</s>
<s>
The	O
server	B-Application
does	O
not	O
support	O
the	O
HTTP	B-Protocol
version	O
used	O
in	O
the	O
request	O
.	O
</s>
<s>
Transparent	O
content	B-Protocol
negotiation	I-Protocol
for	O
the	O
request	O
results	O
in	O
a	O
circular	O
reference	O
.	O
</s>
<s>
The	O
server	B-Application
is	O
unable	O
to	O
store	O
the	O
representation	O
needed	O
to	O
complete	O
the	O
request	O
.	O
</s>
<s>
The	O
server	B-Application
detected	O
an	O
infinite	O
loop	O
while	O
processing	O
the	O
request	O
(	O
sent	O
instead	O
of	O
208	O
Already	O
Reported	O
)	O
.	O
</s>
<s>
Further	O
extensions	O
to	O
the	O
request	O
are	O
required	O
for	O
the	O
server	B-Application
to	O
fulfil	O
it	O
.	O
</s>
<s>
Intended	O
for	O
use	O
by	O
intercepting	O
proxies	O
used	O
to	O
control	O
access	O
to	O
the	O
network	O
(	O
e.g.	O
,	O
"	O
captive	O
portals	O
"	O
used	O
to	O
require	O
agreement	O
to	O
Terms	O
of	O
Service	O
before	O
granting	O
full	O
Internet	O
access	O
via	O
a	O
Wi-Fi	B-Application
hotspot	I-Application
)	O
.	O
</s>
<s>
Used	O
by	O
the	O
Laravel	B-Language
Framework	I-Language
when	O
a	O
CSRF	O
Token	O
is	O
missing	O
or	O
expired	O
.	O
</s>
<s>
A	O
deprecated	O
response	O
used	O
by	O
the	B-Application
Spring	I-Application
Framework	I-Application
when	O
a	O
method	O
has	O
failed	O
.	O
</s>
<s>
Returned	O
by	O
version	O
1	O
of	O
the	O
Twitter	B-Application
Search	O
and	O
Trends	O
API	O
when	O
the	O
client	O
is	O
being	O
rate	O
limited	O
;	O
versions	O
1.1	O
and	O
later	O
use	O
the	O
429	O
Too	O
Many	O
Requests	O
response	O
code	O
instead	O
.	O
</s>
<s>
Returned	O
by	O
ArcGIS	B-Application
for	I-Application
Server	I-Application
.	O
</s>
<s>
Returned	O
by	O
ArcGIS	B-Application
for	I-Application
Server	I-Application
.	O
</s>
<s>
The	O
server	B-Application
has	O
exceeded	O
the	O
bandwidth	O
specified	O
by	O
the	O
server	B-Application
administrator	O
;	O
this	O
is	O
often	O
used	O
by	O
shared	O
hosting	O
providers	O
to	O
limit	O
the	O
bandwidth	O
of	O
customers	O
.	O
</s>
<s>
Used	O
by	O
Qualys	O
in	O
the	O
SSLLabs	O
server	B-Application
testing	O
API	O
to	O
signal	O
that	O
the	O
site	O
ca	O
n't	O
process	O
the	O
request	O
.	O
</s>
<s>
Used	O
by	O
some	O
HTTP	B-Protocol
proxies	O
to	O
signal	O
a	O
network	O
read	O
timeout	O
behind	O
the	O
proxy	B-Application
to	O
a	O
client	O
in	O
front	O
of	O
the	O
proxy	B-Application
.	O
</s>
<s>
An	O
error	O
used	O
by	O
some	O
HTTP	B-Protocol
proxies	O
to	O
signal	O
a	O
network	O
connect	O
timeout	O
behind	O
the	O
proxy	B-Application
to	O
a	O
client	O
in	O
front	O
of	O
the	O
proxy	B-Application
.	O
</s>
<s>
Microsoft	O
's	O
Internet	B-Application
Information	I-Application
Services	I-Application
(	O
IIS	O
)	O
web	O
server	B-Application
expands	O
the	O
4xx	O
error	O
space	O
to	O
signal	O
errors	O
with	O
the	O
client	B-Protocol
's	I-Protocol
request	I-Protocol
.	O
</s>
<s>
The	O
server	B-Application
cannot	O
honour	O
the	O
request	O
because	O
the	O
user	O
has	O
not	O
provided	O
the	O
required	O
information	O
.	O
</s>
<s>
Used	O
in	O
Exchange	B-Protocol
ActiveSync	I-Protocol
when	O
either	O
a	O
more	O
efficient	O
server	B-Application
is	O
available	O
or	O
the	O
server	B-Application
cannot	O
access	O
the	O
users	O
 '	O
mailbox	O
.	O
</s>
<s>
The	O
client	O
is	O
expected	O
to	O
re-run	O
the	O
HTTP	B-Protocol
AutoDiscover	O
operation	O
to	O
find	O
a	O
more	O
appropriate	O
server	B-Application
.	O
</s>
<s>
IIS	O
sometimes	O
uses	O
additional	O
decimal	O
sub-codes	O
for	O
more	O
specific	O
information	O
,	O
however	O
these	O
sub-codes	O
only	O
appear	O
in	O
the	O
response	O
payload	O
and	O
in	O
documentation	O
,	O
not	O
in	O
the	O
place	O
of	O
an	O
actual	O
HTTP	B-Protocol
status	O
code	O
.	O
</s>
<s>
The	O
nginx	B-Operating_System
web	O
server	B-Application
software	I-Application
expands	O
the	O
4xx	O
error	O
space	O
to	O
signal	O
issues	O
with	O
the	O
client	B-Protocol
's	I-Protocol
request	I-Protocol
.	O
</s>
<s>
Used	O
internally	O
to	O
instruct	O
the	O
server	B-Application
to	O
return	O
no	O
information	O
to	O
the	O
client	O
and	O
close	O
the	O
connection	O
immediately	O
.	O
</s>
<s>
An	O
expansion	O
of	O
the	O
400	O
Bad	O
Request	O
response	O
code	O
,	O
used	O
when	O
the	O
client	O
has	O
made	O
a	O
HTTP	B-Protocol
request	O
to	O
a	O
port	O
listening	O
for	O
HTTPS	B-Protocol
requests	O
.	O
</s>
<s>
Used	O
when	O
the	O
client	O
has	O
closed	O
the	O
request	O
before	O
the	O
server	B-Application
could	O
send	O
a	O
response	O
.	O
</s>
<s>
Cloudflare	B-Application
's	O
reverse	O
proxy	B-Application
service	O
expands	O
the	O
5xx	O
series	O
of	O
errors	O
space	O
to	O
signal	O
issues	O
with	O
the	O
origin	O
server	B-Application
.	O
</s>
<s>
The	O
origin	O
server	B-Application
returned	O
an	O
empty	O
,	O
unknown	O
,	O
or	O
unexpected	O
response	O
to	O
Cloudflare	B-Application
.	O
</s>
<s>
The	O
origin	O
server	B-Application
refused	O
connections	O
from	O
Cloudflare	B-Application
.	O
</s>
<s>
Security	O
solutions	O
at	O
the	O
origin	O
may	O
be	O
blocking	O
legitimate	O
connections	O
from	O
certain	O
Cloudflare	B-Application
IP	B-Protocol
addresses	I-Protocol
.	O
</s>
<s>
Cloudflare	B-Application
timed	O
out	O
contacting	O
the	O
origin	O
server	B-Application
.	O
</s>
<s>
Cloudflare	B-Application
could	O
not	O
reach	O
the	O
origin	O
server	B-Application
;	O
for	O
example	O
,	O
if	O
the	O
DNS	O
records	O
for	O
the	O
origin	O
server	B-Application
are	O
incorrect	O
or	O
missing	O
.	O
</s>
<s>
Cloudflare	B-Application
was	O
able	O
to	O
complete	O
a	O
TCP	O
connection	O
to	O
the	O
origin	O
server	B-Application
,	O
but	O
did	O
not	O
receive	O
a	O
timely	O
HTTP	B-Protocol
response	O
.	O
</s>
<s>
Cloudflare	B-Application
could	O
not	O
negotiate	O
a	O
SSL/TLS	B-Protocol
handshake	O
with	O
the	O
origin	O
server	B-Application
.	O
</s>
<s>
Cloudflare	B-Application
could	O
not	O
validate	O
the	O
SSL	O
certificate	O
on	O
the	O
origin	O
web	O
server	B-Application
.	O
</s>
<s>
Also	O
used	O
by	O
Cloud	B-General_Concept
Foundry	I-General_Concept
's	O
gorouter	O
.	O
</s>
<s>
Error	O
527	O
indicates	O
an	O
interrupted	O
connection	O
between	O
Cloudflare	B-Application
and	O
the	O
origin	O
server	B-Application
's	O
Railgun	O
server	B-Application
.	O
</s>
<s>
The	O
load	O
balancer	O
received	O
an	O
X-Forwarded-For	O
request	O
header	O
with	O
more	O
than	O
30	O
IP	B-Protocol
addresses	I-Protocol
.	O
</s>
<s>
An	O
error	O
around	O
authentication	O
returned	O
by	O
a	O
server	B-Application
registered	O
with	O
a	O
load	O
balancer	O
.	O
</s>
<s>
The	O
following	O
caching	B-Protocol
related	O
warning	O
codes	O
were	O
specified	O
under	O
.	O
</s>
<s>
Unlike	O
the	O
other	O
status	O
codes	O
above	O
,	O
these	O
were	O
not	O
sent	O
as	O
the	O
response	O
status	O
in	O
the	O
HTTP	B-Protocol
protocol	I-Protocol
,	O
but	O
as	O
part	O
of	O
the	O
"	O
Warning	O
"	O
HTTP	B-Protocol
header	I-Protocol
.	O
</s>
<s>
Since	O
this	O
"	O
Warning	O
"	O
header	O
is	O
often	O
neither	O
sent	O
by	O
servers	O
nor	O
acknowledged	O
by	O
clients	O
,	O
this	O
header	O
and	O
its	O
codes	O
were	O
obsoleted	O
by	O
the	O
HTTP	B-Protocol
Working	O
Group	O
in	O
2022	O
with	O
.	O
</s>
<s>
The	O
cache	O
was	O
unable	O
to	O
validate	O
the	O
response	O
,	O
due	O
to	O
an	O
inability	O
to	O
reach	O
the	O
origin	O
server	B-Application
.	O
</s>
<s>
Added	O
by	O
a	O
proxy	B-Application
if	O
it	O
applies	O
any	O
transformation	O
to	O
the	O
representation	O
,	O
such	O
as	O
changing	O
the	O
content	O
encoding	O
,	O
media	B-Application
type	I-Application
or	O
the	O
like	O
.	O
</s>
