In the NORWEGIAN ENCYCLOPEDIA shows Karl 1 Knutsson Bonde birthdate & death date as:
KARL 1 KNUTSSON BONDE
Karl I Knutsson Bonde, Karl Knutsson Bonde
BORN October 1, 1408, Finland
DEATH 15 August 1470, Stockholm Castle, begr. in Riddarholmskyrkan, Stockholm
https://snl.no/Karl_1_Knutsson_Bonde
Also from NORWEGIAN BIOGRAPHICAL LEXICON : also shows his birth and death date as
box KARL 1 KNUTSSON BONDE
BORN October 1, 1408, Finland
DEATH 15 May 1470, Stockholm Castle, begr. in Riddarholmskyrkan, Stockholm
el. 1409.0.0
https://nbl.snl.no/Karl_1_Knutsson_Bonde
He writes his testament in 1470 https://sok.riksarkivet.se/sdhk?EndastDigitaliserat=false&Datum...
At the Riksarkivet entry about his testament it is noted: Before 14700515.
That would mean that those historians consider May 15 as the day of his death.
The day of his testament is not known and the testament itself is not existing it seems.
It is noted that the testament is known through copies, among others the Horn collection.
We don’t know what was actually written in the testament from the entry in Riksarkivet. Perhaps there isn’t even a full copy.
It is strange that there are different dates given in Sweden and as Gerene noted in Norway. Reasons for this could be: date conversions or that his funeral date was given as his death date or that a church service was given at another date.
I have written to a professor at STORE NORSKE LEKSIKON and asked for correction of the death date at https://snl.no/Karl_1_Knutsson_Bonde.
Gerene, you have the eyes of a falcon! Thank you! So he died in May. There should be a description of the funeral and services around it. Did anyone see any such things?
From what I have understood he had been ill for a while before he died. It would be interesting to know more about his illness and last days.
Svar på melding i Store norske leksikon fra Erik Opsahl:
Hei Dan! Takk skal du ha! Du har helt rett, og i artikkelen om Karl Knutsson som jeg har skrevet i Norsk biografisk leksikon som det ligger lenke til, er dødsdagen satt til 15.mai 1470. Den foreliggende artikkelen er hentet inn fra den opprinnelige trykte utgaven av leksikonet, og er skrevet av en annen forfatter, og den har jeg ikke rukket å redigere ennå. Det må nok gjøres på lengre sikt, men inntil da, har jeg ihvertfall endret dødsdatoen. Vennlig hilsen Erik