fetch failed - error on npm start on production

now I get this error:
<< query #1 post.hello {
  input: { text: 'from tRPC server!' },
  result: transformResult_9a244fe7_TRPCClientError: fetch failed
      at transformResult_9a244fe7_TRPCClientError.from (/Users/ippo/tRPC-TEST/t3-next13-app/.next/server/chunks/376.js:340:16)
      at /Users/ippo/tRPC-TEST/t3-next13-app/.next/server/chunks/376.js:791:89
      at runNextTicks (node:internal/process/task_queues:60:5)
      at listOnTimeout (node:internal/timers:533:9)
      at process.processTimers (node:internal/timers:507:7) {
    meta: undefined,
    shape: undefined,
    data: undefined,
    [cause]: TypeError: fetch failed
        at Object.fetch (node:internal/deps/undici/undici:11118:11)
        at runNextTicks (node:internal/process/task_queues:60:5)
        at listOnTimeout (node:internal/timers:533:9)
        at process.processTimers (node:internal/timers:507:7) {
      cause: [InvalidArgumentError]
    }
  },
  elapsedMs: 8,
  context: {}
}
(node:19274) ExperimentalWarning: The Fetch API is an experimental feature. This feature could change at any time
(Use `node --trace-warnings ...` to show where the warning was created)
transformResult_9a244fe7_TRPCClientError: fetch failed
    at transformResult_9a244fe7_TRPCClientError.from (/Users/ippo/tRPC-TEST/t3-next13-app/.next/server/chunks/376.js:340:16)
    at /Users/ippo/tRPC-TEST/t3-next13-app/.next/server/chunks/376.js:791:89
.......
.......
[Error: An error occurred in the Server Components render. The specific message is omitted in production builds to avoid leaking sensitive details. A digest property is included on this error instance which may provide additional details about the nature of the error.] {
  digest: '4145997467'