The adapter operation was aborted in ember FASTBOOT mode

Working Ember app Environment:

DEBUG: -------------------------------
index.js:194 DEBUG: Ember             : 3.14.1
index.js:194 DEBUG: Ember Data        : 3.13.1
index.js:194 DEBUG: jQuery            : 3.4.1
index.js:194 DEBUG: Ember Bootstrap   : 2.8.1
index.js:194 DEBUG: Ember Simple Auth : 2.1.0
index.js:194 DEBUG: -------------------------------

emebr Frontend works on localhost:4200

php Backend works on localhost:8000

NOTE: http://localhost:4200/?fastboot=false - works as expected on the same server and configuration

I have a problem with dataAdapter after installing fastboot.

export default DS.JSONAPIAdapter.extend({
  host: 'http://localhost:8000', # the app do not crash when I disable this line in fastboot
  namespace: 'api/v1',
});

Log:

Error: The adapter operation was aborted
    at ErrorClass.AdapterError (/tmp/broccoli-15ZQyaTQRX5gGt/out-370-append_ember_auto_import_analyzer/assets/addon-tree-output/@ember-data/adapter/error.js:93:1)
    at new ErrorClass (/tmp/broccoli-15ZQyaTQRX5gGt/out-370-append_ember_auto_import_analyzer/assets/addon-tree-output/@ember-data/adapter/error.js:127:1)
    at handleAbort (/tmp/broccoli-15ZQyaTQRX5gGt/out-370-append_ember_auto_import_analyzer/assets/addon-tree-output/@ember-data/adapter/rest.js:1165:1)
    at ajaxError (/tmp/broccoli-15ZQyaTQRX5gGt/out-370-append_ember_auto_import_analyzer/assets/addon-tree-output/@ember-data/adapter/rest.js:1137:1)
    at ajaxErrorHandler (/tmp/broccoli-15ZQyaTQRX5gGt/out-370-append_ember_auto_import_analyzer/assets/addon-tree-output/@ember-data/adapter/rest.js:1197:1)
    at Object.hash.error (/tmp/broccoli-15ZQyaTQRX5gGt/out-370-append_ember_auto_import_analyzer/assets/addon-tree-output/@ember-data/adapter/rest.js:913:1)
    at fire (/app/node_modules/jquery-deferred/lib/jquery-callbacks.js:78:30)
    at Object.fireWith (/app/node_modules/jquery-deferred/lib/jquery-callbacks.js:188:7)
    at Object.fire [as reject] (/app/node_modules/jquery-deferred/lib/jquery-callbacks.js:195:10)
    at ClientRequest.onError (/app/node_modules/najax/lib/najax.js:208:9)
    at emitOne (events.js:116:13)
    at ClientRequest.emit (events.js:211:7)
    at Socket.socketErrorListener (_http_client.js:401:9)
    at emitOne (events.js:116:13)
    at Socket.emit (events.js:211:7)
    at emitErrorNT (internal/streams/destroy.js:66:8)
    at _combinedTickCallback (internal/process/next_tick.js:139:11)
    at process._tickDomainCallback (internal/process/next_tick.js:219:9)

Tried to use proxy as ember server --proxy=http://127.0.0.1:8000

Error proxying to http://127.0.0.1:8000
nodejs_1      | connect ECONNREFUSED 127.0.0.1:8000

Ready to provide additional logs & information