Root cause analysis: (user-partitions (append (auto-partition disk #:scheme scheme) (create-special-user-partitions (disk-partitions disk))))) <---
(define (create-special-user-partitions partitions) "Return a list with a <user-partition> record describing the ESP partition found in PARTITIONS, if any." (filter-map (lambda (partition) (and (esp-partition? partition) (partition->user-partition partition))) <---- partitions)) I think create-special-user-partitions and the form above is automatically trying to keep existing UEFI ESP partitions of the user. And partition->user-partition failed for (existing) fat16 partitions. So the fix of adding fat16 was definitely the right one for that specific file system type. It should be fine now.
pgptiUn4b25Bo.pgp
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