Update
Bitcoin Core 32.0 Graphical Wallet Creates PSBT v2 Files
Bitcoin Core 32.0’s graphical wallet has introduced PSBT v2 files, which older Core wallets reportedly cannot import. This issue has been moved to the 32.1 milestone, and users can select the older format through RPC. The problem concerns the Partially Signed Bitcoin Transaction (PSBT) format used for exchanging transaction data during signing.