"Failed to check balance for 'any address that its checking': invalid character '<' looking for beginning of value"

[hw9da]

Program works well at the start, but after around 1-2 minutes it gives me this error -

"2024/02/14 20:02:46 Worker 36: Failed to check balance for 18LRpf9BWypZJLFTNL7nsxToP1EsWREpiK: invalid character '<' looking for beginning of value"

Also there is another error that comes with it.

"2024/02/14 20:10:59 Worker 3987: Failed to check balance for 1Ac3ezAJh91z5X2CixGWEj2NterKBd7pBd: Get "https://api.blockcypher.com/v1/btc/main/addrs/1Ac3ezAJh91z5X2CixGWEj2NterKBd7pBd/balance": read tcp 192.168.0.116:65287->104.20.20.251:443: wsarecv: An existing connection was forcibly closed by the remote host."

Any ideas?

Images of the problem -