HI, I have a problem i don’t understand. I need your help.
what i originally was trying is to swap some lightning funds from a node (say NODE_A) to … whatever (in my case boltz) using a specific channel. (that is a possibility using Thunderhub.
it worked using one of NODE_A channel but didn’t for another one (say a channel to NODE_B) although large funds are there. and the channel enabled. it results in : insufficient balance for payment.
to investigate further :
i then tried just to keysend from NODE_A to NODE_B. just 10 sats. and that resulted in :
“cannot return null for non-nullable field payinvoice.is_confirmed. keysend lightning network”
although Keysend are acccepted ( configured as enable on the advance setting parameters on UMbrel Lingthnig App)
finally i tried the other way . to keysend from NODE_B to NODE_A . that resulted in 
PaymentPathfindingFailedToFindPossibleRoute … when there is a direct , enabled channel from NoDE_B to NODE_A.
i’d like to understand what are those messages and why it behaves like that … ( a conf problem ?).
it looks like a sign the channel has pb. but maybe so has node_B so i’d prefer to understand what is going on instead of just closing that channel.
thanks a lot lot if you can help or give me more things to try to pinpoint the problem.