org.openqa.selenium.SessionNotCreatedException: Could not start a new session. Response code 500. Message: null

I am trying to run my automation test using java-client:8.0.0 beta version on a experitest cloud platform but while running the test getting the below issue.

Code:

protected IOSDriver driver = null;
DesiredCapabilities dc = new DesiredCapabilities();

@BeforeEach
public void setUp()  {

    dc.setCapability("testName", "Quick Start iOS Native Demo");
    dc.setCapability("accessKey", accessKey);
    dc.setCapability("deviceQuery", "@os='ios' and @category='TABLET'");

    dc.setCapability(MobileCapabilityType.APP, "cloud:com.experitest.ExperiBank");
    dc.setCapability(IOSMobileCapabilityType.BUNDLE_ID, "com.experitest.ExperiBank");

    try {
        driver = new IOSDriver(new URL("https://specsavers.experitest.com/wd/hub"), dc);

    } catch (MalformedURLException e) {
        e.printStackTrace();
    }
}

@Test
public void quickStartiOSNativeDemo() {
    driver.rotate(ScreenOrientation.PORTRAIT);
    driver.findElement(By.xpath("//*[@id='usernameTextField']")).sendKeys("company");
    driver.hideKeyboard();
    driver.findElement(By.xpath("//*[@id='passwordTextField']")).sendKeys("company");
    driver.findElement(By.xpath("//*[@id='loginButton']")).click();
    driver.findElement(By.xpath("//*[@id='makePaymentButton']")).click();
    driver.findElement(By.xpath("//*[@id='phoneTextField']")).sendKeys("0541234567");
    driver.findElement(By.xpath("//*[@id='nameTextField']")).sendKeys("Jon Snow");
    driver.findElement(By.xpath("//*[@id='amountTextField']")).sendKeys("50");
    driver.findElement(By.xpath("//*[@id='countryButton']")).click();
    driver.findElement(By.xpath("//*[@id='Switzerland']")).click();
    driver.findElement(By.xpath("//*[@id='sendPaymentButton']")).click();
    driver.findElement(By.xpath("//*[@id='Yes']")).click();
}

@AfterEach
public void tearDown() {
    System.out.println("Report URL: "+ driver.getCapabilities().getCapability("reportUrl"));
    driver.quit();
}

Error log


Build info: version: '4.0.0', revision: '3a21814679'
System info: host: 'UKC-DSEV023991', ip: '110.4.197.09', os.name: 'Windows 10', os.arch: 'amd64', os.version: '10.0', java.version: '1.8.0_281'
Driver info: io.appium.java_client.ios.IOSDriver
Command: [null, newSession {capabilities=[{appium:accessKey=546456gfgdfgk, appium:app=cloud:com.experitest.ExperiBank, appium:bundleId=com.experitest.ExperiBank, appium:deviceName= IPad (5th Generation) SPEC-0002, appium:deviceQuery=@os='ios' and @category='TABLET', platformName=iOS, appium:platformVersion=8.1, appium:testName=Quick Start iOS Native Demo}], desiredCapabilities=Capabilities {accessKey: eyJ4cC51IjoxMywieHAucCI6MSw..., app: cloud:com.experitest.Experi..., bundleId: com.experitest.ExperiBank, deviceName:  IPad (5th Generation) SPEC..., deviceQuery: @os='ios' and @category='TA..., platformName: iOS, platformVersion: 8.1, testName: Quick Start iOS Native Demo}}]
Capabilities {}

    at org.openqa.selenium.remote.ProtocolHandshake.createSession(ProtocolHandshake.java:126)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at io.appium.java_client.remote.AppiumProtocolHandshake.createSession(AppiumProtocolHandshake.java:126)
    at io.appium.java_client.remote.AppiumProtocolHandshake.createSession(AppiumProtocolHandshake.java:102)
    at io.appium.java_client.remote.AppiumCommandExecutor.createSession(AppiumCommandExecutor.java:146)
    at io.appium.java_client.remote.AppiumCommandExecutor.execute(AppiumCommandExecutor.java:180)
    at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:559)
    at io.appium.java_client.AppiumDriver.startSession(AppiumDriver.java:225)
    at org.openqa.selenium.remote.RemoteWebDriver.<init>(RemoteWebDriver.java:168)
    at io.appium.java_client.AppiumDriver.<init>(AppiumDriver.java:79)
    at io.appium.java_client.AppiumDriver.<init>(AppiumDriver.java:87)
    at io.appium.java_client.ios.IOSDriver.<init>(IOSDriver.java:105)```

appium / java-client

org.openqa.selenium.SessionNotCreatedException: Could not start a new session. Response code 500. Message: null #1649