Error when migrate to Loom (extDev)

[babo105]

Hi,

Versions:
Truffle v5.3.1 (core: 5.3.1)
Solidity v0.5.16 (solc-js)
Node v14.16.0
Web3.js v1.3.5

Modification to make the code runnable:
./loom/trufle-config.js added: "evmVersion: 'constantinople'" and modified compiler "version: '^0.5.0'"
./loom/contracts/*.sol modified: change pragma from '0.5.0' to '^0.5.0'

Then run with npm run migrate:loom

>npm run migrate:loom

> [email protected] migrate:loom x:\github\loom-examples
>  cd loom && npx truffle migrate --network extdev --reset -all


Compiling your contracts...
===========================
| Fetching solc version list from solc-bin. Attempt #1
...
...
...
Error detected within Truffle process: {
  kind: 'error',
  url: 'wss://extdev-plasma-us1.dappchains.com/queryws',
  error: Error: Unexpected server response: 521
      at ClientRequest.<anonymous> (x:\github\loom-examples\node_modules\rpc-websockets\node_modules\ws\lib\websocket.js:542:5)
      at ClientRequest.emit (events.js:315:20)
      at HTTPParser.parserOnIncomingClient [as onIncoming] (_http_client.js:641:27)
      at HTTPParser.parserOnHeadersComplete (_http_common.js:126:17)
      at TLSSocket.socketOnData (_http_client.js:509:22)
      at TLSSocket.emit (events.js:315:20)
      at addChunk (internal/streams/readable.js:309:12)
      at readableAddChunk (internal/streams/readable.js:284:9)
      at TLSSocket.Readable.push (internal/streams/readable.js:223:10)
      at TLSWrap.onStreamRead (internal/stream_base_commons.js:188:23)
}
Error detected within Truffle process: {
  kind: 'error',
  url: 'wss://extdev-plasma-us1.dappchains.com/websocket',
  error: Error: Unexpected server response: 521
      at ClientRequest.<anonymous> (x:\github\loom-examples\node_modules\rpc-websockets\node_modules\ws\lib\websocket.js:542:5)
      at ClientRequest.emit (events.js:315:20)
      at HTTPParser.parserOnIncomingClient [as onIncoming] (_http_client.js:641:27)
      at HTTPParser.parserOnHeadersComplete (_http_common.js:126:17)
      at TLSSocket.socketOnData (_http_client.js:509:22)
      at TLSSocket.emit (events.js:315:20)
      at addChunk (internal/streams/readable.js:309:12)
      at readableAddChunk (internal/streams/readable.js:284:9)
      at TLSSocket.Readable.push (internal/streams/readable.js:223:10)
      at TLSWrap.onStreamRead (internal/stream_base_commons.js:188:23)
}
Error: There was a timeout while attempting to connect to the network.
       Check to see that your provider is valid.
       If you have a slow internet connection, try configuring a longer timeout in your Truffle config. Use the networks[networkName].networkCheckTimeout property to do this.
    at Timeout._onTimeout (x:\github\loom-examples\loom\node_modules\truffle\build\webpack:\packages\provider\index.js:56:1)
    at listOnTimeout (internal/timers.js:554:17)
    at processTimers (internal/timers.js:497:7)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! [email protected] migrate:loom: ` cd loom && npx truffle migrate --network extdev --reset -all`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the [email protected] migrate:loom script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in...