Updating, stakepool registration-certificate error

I wanted to do some updates on the metadatafile, suddenly I got the following error when running the cardano-cli stake-pool registration-certificate:

cardano-cli: Cannot decode byte ‘\x82’: Data.Text.Internal.Encoding.decodeUtf8: Invalid UTF-8 stream

Anyone knows what the cause can be?

kind regards,

Marc

file -i node.skey
node.skey: application/octet-stream; charset=binary

So the file node.skey seems to be binary at my machine.
I am doubting if the file should be a charset=us-ascii file?

Can someone confirm what the file type should be?

you can run the command: file -i node.skey in your folder.

Thanks in advance.

Edit:
I converted the node.vkey to UTF-8, now it says Error: node.vkey: Invalid key.