Looks like your error is coming from the rococo pallet with index 31 so that would be the AssignedSlots pallet, and specifically Error 1 which is Cannot Onboard:
Para cannot be onboarded because it is already tracked by our system.
Which makes sense in your case because you mentioned that you are looking to extend therefore you're already in the system...
So the issue that I see is a couple things...
The sudo
key is currently controlled by Parity Tech:
The Rococo sudo
key is controlled by Parity tech at this time, so to
have the operation required to get a slot, please place a request on
the Parachain Technical matrix channel once you complete the above and
are ready to connect! They will initiate the slot for you ASAP.
At this point, requesting a permanent or temporary parachain slot
still a privileged (sudo) operation to be performed by the (Rococo)
test chain's operator (using a call to the assignedSlots pallet's
dispatchable functions) but the long-term plan is to make it a
community-driven process via Rococo's governance framework.
Additionally, if you have already been approved and downgraded from your slot:
Please do note that when your temporary slot's lease ends, the
parachain is automatically downgraded to a parathread. Registered and
approved slots are cycled through automatically in a round-robin
fashion, so you will expect to come back online as a parachain from
time to time.
A note on Temporary Parachain Slots on Rococo:
Temporary slots are parachain slots that are dynamically allocated in
a continuous rollover manner. Concretely, at every start of a lease
period, a certain number of parathreads (up to a maximum defined in
the relay chain's configuration) will be automatically upgraded to
parachains for a certain duration. The parachains that were active
during the ending lease period will be automatically downgraded to
parathreads to free the slots for others to use in the subsequent one.