Transferring suggested min or max amount to spending results in `Client error: Invalid request format`

[piotr-iohk]

Observed while testing on the backend from e2e tests (see: bitkit-e2e-tests/docker).

Steps to reproduce:

1. Have a fresh wallet and fund it with, say, 1 000 000 btc.
2. Try to transfer suggested min or max amount to spending. (Or some other amount close to min or max)

Actual:
Transfer results with an error toast message:

DataException='errorDetails=Failed to create order with Blocktank client: Client error: Invalid request format'

In the log there is:

2025-10-01 13:19:49.420 UTC] INFOℹ️: Buying channel with lspBalanceSat: 6232, channelExpiryWeeks: 6, options: CreateOrderOptions(clientBalanceSat=3116, lspNodeId=null, couponCode=, source=bitkit-android, discountCode=null, zeroConf=true, zeroConfPayment=false, zeroReserve=true, clientNodeId=039d9fd563228cdd6fcd6019e743200e5f41783e2c54600f677627c2899411f36d, signature=d6ee198bdcqwaeeksnu81fj5crhatu5pspoqyf8npn6qz8n5hr3eqyhnekwwx6msgnfgr8pt5a37g1sdws6fo13dcq4pp3aqdahdiyn9, timestamp=2025-10-01T13:19:49Z, refundOnchainAddress=null, announceChannel=false) - BlocktankRepo [BlocktankRepo.kt:225]
[2025-10-01 13:19:49.473 UTC] ERROR❌️: ServiceQueue.CORE error [DataException='errorDetails=Failed to create order with Blocktank client: Client error: Invalid request format'] [ServiceQueue.kt:50]
[2025-10-01 13:19:49.474 UTC] ERROR❌️: Failed to create order [AppError='DataException='errorDetails=Failed to create order with Blocktank client: Client error: Invalid request format''] - BlocktankRepo [BlocktankRepo.kt:240]

Expected:
Successful transfer.

See video:

transfer-errors.webm

See exemplary logs:

logs_invalid_requests.zip

[ovitrif]

Sidenote: we really need to update bitkit-core to send us (the client apps) logs with the actual request/response body.

[piotr-iohk]

Note: Perhaps it is not the min, max per se but depends more on the amount being transferred. I observed that for savings balance of 100 000 the 25% was failing which was calculated at around 24 972:

100l-savings-25pcnt-transfer.webm

[ovitrif]

This has been fixed recently, with the refactor of transfer limits and hoisting the logic to bitkit-core.