[XCUITest] SyntaxError: Unexpected token < in JSON at position 0'

The problem

Seeing Unexpected token < in JSON at position 0’ after simulator is triggered.

Environment

• Appium version (or git revision) that exhibits the issue: v1.6.0
• Last Appium version that did not exhibit the issue (if applicable): v 1.5.3
• Desktop OS/version used to run Appium: MAC OS X EI Capitan 10.11.6
• Node.js version (unless using Appium.app|exe): v6.7.0
• Mobile platform/version under test: IOS/10.0
• Real device or emulator/simulator: Simulator
• Appium CLI or Appium.app|exe: Appium.app

Details

On trying to run a test case, I am seeing this error ‘[XCUITest] SyntaxError: Unexpected token < in JSON at position 0’. Please take a look into the below log.

node . --app /Users/abc/Desktop/xxx.app
[Appium] Welcome to Appium v1.6.0
[Appium] Non-default server args:
[Appium] app: '/Users/abc/Desktop/xxx.app'
[Appium] Deprecated server args:
[Appium] --app => --default-capabilities '{"app":"/Users/abc/Desktop/xxx.app"}'
[Appium] Default capabilities, which will be added to each request unless overridden by desired capabilities:
[Appium] app: '/Users/abc/Desktop/xxx.app'
[Appium] Appium REST http interface listener started on 0.0.0.0:4723
[HTTP] --> POST /wd/hub/session {"desiredCapabilities":{"newCommandTimeout":360000,"platform":"MAC","platformVersion":"10.0","platformName":"iOS","deviceName":"iPhone 6","autoDismissAlerts":true}}
[MJSONWP] Calling AppiumDriver.createSession() with args: [{"newCommandTimeout":36000...
[Appium] Requested iOS support with version >= 10, using XCUITest driver instead of UIAutomation-based driver, since the latter is unsupported on iOS 10 and up.
[Appium] Creating new XCUITestDriver session
[Appium] Capabilities:
[Appium] newCommandTimeout: 360000
[Appium] platform: 'MAC'
[Appium] platformVersion: '10.0'
[Appium] platformName: 'iOS'
[Appium] deviceName: 'iPhone 6'
[Appium] autoDismissAlerts: true
[Appium] app: '/Users/abc/Desktop/xxx.app'
[debug] [XCUITest] XCUITestDriver version: 2.0.25
[BaseDriver] The following capabilities were provided, but are not recognized by appium: platform.
[BaseDriver] Session created with session id: 458b8ebe-d810-42f0-806d-ca5b6edb5de5
[debug] [XCUITest] Xcode version set to '8.0'
[debug] [XCUITest] iOS SDK Version set to '10.0'
[iOSSim] Constructing iOS simulator for Xcode version 8.0 with udid 'E423110B-107C-482C-9BFC-38AC3A9D05A2'
[XCUITest] Determining device to run tests on: udid: 'E423110B-107C-482C-9BFC-38AC3A9D05A2', real device: false
[BaseDriver] Using local app '/Users/abc/Desktop/xxx.app'
[debug] [XCUITest] Checking whether app is actually present
[debug] [ios-app-utils] Getting bundle ID from app
[debug] [iOSLog] Starting iOS 10.0 simulator log capture
[debug] [iOSLog] System log path: /Users/abc/Library/Logs/CoreSimulator/E423110B-107C-482C-9BFC-38AC3A9D05A2/system.log
[XCUITest] Setting up simulator
[debug] [iOS] No reason to set locale
[debug] [iOS] No iOS / app preferences to set
[XCUITest] Simulator with udid 'E423110B-107C-482C-9BFC-38AC3A9D05A2' not booted. Booting up now
[debug] [iOSSim] Killing all iOS Simulators
[iOSSim] Starting simulator with command: open /Applications/Xcode.app/Contents/Developer/Applications/Simulator.app --args -CurrentDeviceUDID E423110B-107C-482C-9BFC-38AC3A9D05A2
[iOSSim] Tailing simulator logs until we encounter the string "SMS Plugin initialized"
[iOSSim] We will time out after 60000ms
[debug] [iOSSim] Waiting an extra 10000ms for the simulator to really finish booting
[debug] [iOSSim] Done waiting extra time for simulator
[iOSSim] Simulator booted in 13688ms
[debug] [XCUITest] Installing app '/Users/abc/Desktop/xxx.app' on device
[XCUITest] Using default agent: /Users/abc/Downloads/appium-1.6.0/node_modules/appium-xcuitest-driver/WebDriverAgent/WebDriverAgent.xcodeproj
[XCUITest] Using default bootstrap: /Users/abc/Downloads/appium-1.6.0/node_modules/appium-xcuitest-driver/WebDriverAgent
[XCUITest] Launching WebDriverAgent on the device
[debug] [XCUITest] Carthage found: /usr/local/bin/carthage
[debug] [XCUITest] Beginning test with command 'xcodebuild build test -project /Users/abc/Downloads/appium-1.6.0/node_modules/appium-xcuitest-driver/WebDriverAgent/WebDriverAgent.xcodeproj -scheme WebDriverAgentRunner -destination id=E423110B-107C-482C-9BFC-38AC3A9D05A2 -configuration Debug' in directory '/Users/abc/Downloads/appium-1.6.0/node_modules/appium-xcuitest-driver/WebDriverAgent'
[XCUITest] Waiting for WebDriverAgent to start on device
[debug] [XCUITest] Log file for xcodebuild test: /Users/abc/Library/Developer/Xcode/DerivedData/WebDriverAgent-dfdievcxyrzumfawcyrwmemylwmf/Logs/Test/9AEF6490-9D30-45CA-8E5B-05588B56018B/Session-WebDriverAgentRunner-2016-10-13_124248-GDoOSh.log
[debug] [WebDriverAgent] Sim: Oct 13 12:42:50 CoreSimulatorBridge[37846]: Requesting installation of file:///Users/abc/Library/Developer/Xcode/DerivedData/WebDriverAgent-dfdievcxyrzumfawcyrwmemylwmf/Build/Products/Debug-iphonesimulator/WebDriverAgentRunner-Runner.app/ with options: {
[debug] [WebDriverAgent] Sim: CFBundleIdentifier = "com.apple.test.WebDriverAgentRunner-Runner";
[debug] [WebDriverAgent] Sim: PackageType = Developer;
[debug] [WebDriverAgent] Sim: SimulatorRootPath = "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk";
[debug] [WebDriverAgent] Sim: SimulatorUserPath = "/Users/abc/Library/Developer/CoreSimulator/Devices/E423110B-107C-482C-9BFC-38AC3A9D05A2/data";
[debug] [WebDriverAgent] Sim: }
[debug] [WebDriverAgent] Sim: Oct 13 12:42:53 CoreSimulatorBridge[37846]: Requesting launch of com.apple.test.WebDriverAgentRunner-Runner with options: {
[debug] [WebDriverAgent] Sim: arguments = (
[debug] [WebDriverAgent] Sim: "-NSTreatUnknownArgumentsAsOpen",
[debug] [WebDriverAgent] Sim: NO,
[debug] [WebDriverAgent] Sim: "-ApplePersistenceIgnoreState",
[debug] [WebDriverAgent] Sim: YES
[debug] [WebDriverAgent] Sim: );
[debug] [WebDriverAgent] Sim: environment = {
[debug] [WebDriverAgent] Sim: "DTX_CONNECTION_SERVICES_PATH" = "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/Developer/Library/PrivateFrameworks/DTXConnectionServices.framework";
[debug] [WebDriverAgent] Sim: "DYLD_FRAMEWORK_PATH" = "/Users/abc/Library/Developer/Xcode/DerivedData/WebDriverAgent-dfdievcxyrzumfawcyrwmemylwmf/Build/Products/Debug-iphonesimulator:/Users/abc/Library/Developer/Xcode/DerivedData/WebDriverAgent-dfdievcxyrzumfawcyrwmemylwmf/Build/Products/Debug-iphonesimulator:/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/Library/Frameworks";
[debug] [WebDriverAgent] Sim: "DYLD_LIBRARY_PATH" = "/Users/abc/Library/Developer/Xcode/DerivedData/WebDriverAgent-dfdievcxyrzumfawcyrwmemylwmf/Build/Products/Debug-iphonesimulator:/Users/abc/Library/Developer/Xcode/DerivedData/WebDriverAgent-dfdievcxyrzumfawcyrwmemylwmf/Build/Products/Debug-iphonesimulator:/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/Library/Frameworks";
[debug] [WebDriverAgent] Sim: NSUnbufferedIO = YES;
[debug] [WebDriverAgent] Sim: "OS_ACTIVITY_DT_MODE" = YES;
[debug] [WebDriverAgent] Sim: "XCODE_DBG_XPC_EXCLUSIONS" = "com.apple.dt.xctestSymbolicator";
[debug] [WebDriverAgent] Sim: XCTestConfigurationFilePath = "/var/folders/1m/6m0n2ph10nz85p68w8375m7m01h5tx/T/com.apple.dt.XCTest/C57F2807-C575-45B3-A431-75FC989D8FE8/remote-container/tmp/WebDriverAgentRunner-C57F2807-C575-45B3-A431-75FC989D8FE8.xctestconfiguration";
[debug] [WebDriverAgent] Sim: "__XCODE_BUILT_PRODUCTS_DIR_PATHS" = "/Users/abc/Library/Developer/Xcode/DerivedData/WebDriverAgent-dfdievcxyrzumfawcyrwmemylwmf/Build/Products/Debug-iphonesimulator";
[debug] [WebDriverAgent] Sim: "__XPC_DYLD_FRAMEWORK_PATH" = "/Users/abc/Library/Developer/Xcode/DerivedData/WebDriverAgent-dfdievcxyrzumfawcyrwmemylwmf/Build/Products/Debug-iphonesimulator";
[debug] [WebDriverAgent] Sim: "__XPC_DYLD_LIBRARY_PATH" = "/Users/abc/Library/Developer/Xcode/DerivedData/WebDriverAgent-dfdievcxyrzumfawcyrwmemylwmf/Build/Products/Debug-iphonesimulator";
[debug] [WebDriverAgent] Sim: };
[debug] [WebDriverAgent] Sim: stderr = "/dev/ttys002";
[debug] [WebDriverAgent] Sim: stdout = "/dev/ttys002";
[debug] [WebDriverAgent] Sim: "wait_for_debugger" = 0;
[debug] [WebDriverAgent] Sim: }
[debug] [WebDriverAgent] Sim: Oct 13 12:42:53 CoreSimulatorBridge[37846]: [Common] [FBSSystemService][0x6315] Sending request to open "com.apple.test.WebDriverAgentRunner-Runner"
[debug] [WebDriverAgent] Sim: Oct 13 12:42:53 CoreSimulatorBridge[37846]: [Common] [FBSSystemService][0x6315] Request successful:
[debug] [WebDriverAgent] Sim: Oct 13 12:42:54 XCTRunner[38203]: assertion failed: 15G31 14A345: libxpc.dylib + 62597 [37A9DF49-35C1-3D93-B854-B35CACF0100F]: 0x7d
[debug] [WebDriverAgent] Sim: Oct 13 12:42:54 XCTRunner[38203]: Running tests...
[debug] [WebDriverAgent] Sim: Oct 13 12:43:00 --- last message repeated 4 times ---
[debug] [WebDriverAgent] Sim: Oct 13 12:43:00 XCTRunner[38203]: Continuing to run tests in the background with task ID 1
[debug] [WebDriverAgent] Sim: Oct 13 12:43:00 --- last message repeated 13 times ---
[debug] [WebDriverAgent] Sim: Oct 13 12:43:00 XCTRunner[38203]: Built at Oct 13 2016 12:42:49
[XCUITest] Detected that WebDriverAgent is running at url 'http://10.165.64.160:8100'
[debug] [WebDriverAgent] Sim: Oct 13 12:43:00 XCTRunner[38203]: ServerURLHere->http://10.165.64.160:8100<-ServerURLHere
[XCUITest] WebDriverAgent started at url 'http://10.165.64.160:8100'
[JSONWP Proxy] Proxying [POST /session] to [POST http://localhost:8100/session] with body: {"desiredCapabilities":{"bu...
[XCUITest] SyntaxError: Unexpected token < in JSON at position 0
at Object.parse (native)
at new ProxyRequestError (lib/mjsonwp/errors.js:322:26)
at JWProxy.proxy$ (lib/jsonwp-proxy/proxy.js:122:13)
at tryCatch (/Users/abc/Downloads/appium-1.6.0/node_modules/babel-runtime/regenerator/runtime.js:67:40)
at GeneratorFunctionPrototype.invoke as _invoke
at GeneratorFunctionPrototype.prototype.(anonymous function) as throw
at GeneratorFunctionPrototype.invoke (/Users/abc/Downloads/appium-1.6.0/node_modules/babel-runtime/regenerator/runtime.js:136:37)
SyntaxError: Unexpected token < in JSON at position 0
at Object.parse (native)
at new ProxyRequestError (lib/mjsonwp/errors.js:322:26)
at JWProxy.proxy$ (lib/jsonwp-proxy/proxy.js:122:13)
at tryCatch (/Users/abc/Downloads/appium-1.6.0/node_modules/babel-runtime/regenerator/runtime.js:67:40)
at GeneratorFunctionPrototype.invoke as _invoke
at GeneratorFunctionPrototype.prototype.(anonymous function) as throw
at GeneratorFunctionPrototype.invoke (/Users/abc/Downloads/appium-1.6.0/node_modules/babel-runtime/regenerator/runtime.js:136:37)
[JSONWP Proxy] Proxying [DELETE /session/458b8ebe-d810-42f0-806d-ca5b6edb5de5] to [DELETE http://localhost:8100/session/458b8ebe-d810-42f0-806d-ca5b6edb5de5] with no body
[MJSONWP] Encountered internal error running command: SyntaxError: Unexpected token < in JSON at position 0
at Object.parse (native)
at new ProxyRequestError (lib/mjsonwp/errors.js:322:26)
at JWProxy.proxy$ (lib/jsonwp-proxy/proxy.js:122:13)
at tryCatch (/Users/abc/Downloads/appium-1.6.0/node_modules/babel-runtime/regenerator/runtime.js:67:40)
at GeneratorFunctionPrototype.invoke as _invoke
at GeneratorFunctionPrototype.prototype.(anonymous function) as throw
at GeneratorFunctionPrototype.invoke (/Users/abc/Downloads/appium-1.6.0/node_modules/babel-runtime/regenerator/runtime.js:136:37)
[HTTP] <-- POST /wd/hub/session 500 32786 ms - 177
[debug] [XCUITest] Waiting for WebDriverAgent server to finish loading...
[debug] [XCUITest] Waiting for WebDriverAgent server to finish loading...

[hemche]

I had been following this thread for sometime, the corporate proxy was the culprit. After removing proxy details in bash profile. The app launched like a charm ! Thank you @imurchie @wmkeicher @vishwathma

[imurchie]

You should be able to set your no_proxy for a particular port, so you can narrow it down to the particular Appium port on localhost. Unless you randomly assign the port when running.