The \fBpay\fR RPC command attempts to find a route to the given destination, and send the funds it asks for\&. If the \fIbolt11\fR does not contain an amount, \fImsatoshi\fR is required, otherwise if it is specified it must be \fInull\fR\&. If \fIbolt11\fR contains a description hash (\fIh\fR field) \fIdescription\fR is required, otherwise it is unused\&. The \fIriskfactor\fR is described in detail in lightning\-getroute(7), and defaults to 1\&.0\&.
.sp
The response will occur when the payment fails or succeeds\&. Once a payment has succeeded, calls to \fBpay\fR with the same \fIbolt11\fR will succeed immediately\&.
.SH"RETURN VALUE"
.sp
On success, this returns the payment \fIpreimage\fR which hashes to the \fIpayment_hash\fR to prove that the payment was successful\&.
On error, if the error occurred from a node other than the final destination, the route table will be updated so that getroute(7) should return an alternate route (if any)\&. An error from the final destination implies the payment should not be retried\&.
.sp
The following error codes may occur:
.sp
.RS4
.ien\{\
\h'-04'\(bu\h'+03'\c
.\}
.el\{\
.sp-1
.IP\(bu2.3
.\}
\-1\&. Catchall nonspecific error\&.
.RE
.sp
.RS4
.ien\{\
\h'-04'\(bu\h'+03'\c
.\}
.el\{\
.sp-1
.IP\(bu2.3
.\}
200\&. A previous
\fBsendpay\fR
or
\fBpay\fR
is in progress\&.
.RE
.sp
.RS4
.ien\{\
\h'-04'\(bu\h'+03'\c
.\}
.el\{\
.sp-1
.IP\(bu2.3
.\}
201\&. Already paid with this
\fIhash\fR
using different amount or destination\&.
.RE
.sp
.RS4
.ien\{\
\h'-04'\(bu\h'+03'\c
.\}
.el\{\
.sp-1
.IP\(bu2.3
.\}
202\&. Unparseable onion reply\&. The
\fIdata\fR
field of the error will have a
\fIonionreply\fR
field, a hex string representation of the raw onion reply\&.
.RE
.sp
.RS4
.ien\{\
\h'-04'\(bu\h'+03'\c
.\}
.el\{\
.sp-1
.IP\(bu2.3
.\}
203\&. Permanent failure at destination\&. The
\fIdata\fR
field of the error will be routing failure object\&.
.RE
.sp
.RS4
.ien\{\
\h'-04'\(bu\h'+03'\c
.\}
.el\{\
.sp-1
.IP\(bu2.3
.\}
204\&. Failure along route; retry a different route\&. The
\fIdata\fR
field of the error will be routing failure object\&.