Appium starts application but test gives error “FAIL : No application is open” - appium

Question

The problem:
i use appium+robotframework to test my app.when i use key words:Open Application,it always gets failed result:No application is open.but actually the app was already open.i started appium server with code:appium -p 4723 --session-override --no-reset.
Environment:
info AppiumDoctor ### Diagnostic for necessary dependencies starting ###
info AppiumDoctor ✔ The Node.js binary was found at: C:\Program Files\nodejs\node.EXE
info AppiumDoctor ✔ Node version is 16.15.1
info AppiumDoctor ✔ ANDROID_HOME is set to: D:\Android_Sdk
info AppiumDoctor ✔ JAVA_HOME is set to: C:\Program Files\Java\jdk1.8.0_60
info AppiumDoctor Checking adb, android, emulator
info AppiumDoctor 'adb' is in D:\Android_Sdk\platform-tools\adb.exe
info AppiumDoctor 'android' is in D:\Android_Sdk\tools\android.bat
info AppiumDoctor 'emulator' is in D:\Android_Sdk\emulator\emulator.exe
info AppiumDoctor ✔ adb, android, emulator exist: D:\Android_Sdk
info AppiumDoctor ✔ 'bin' subfolder exists under 'C:\Program Files\Java\jdk1.8.0_60'
info AppiumDoctor ### Diagnostic for necessary dependencies completed, no fix needed. ###
Log:
in robotframework,i runed the test in debug,there some info:
20220802 18:05:05.399 : DEBUG : Starting new HTTP connection (1): 127.0.0.1:4723
20220802 18:05:14.770 : DEBUG : http://127.0.0.1:4723 "POST /wd/hub/session HTTP/1.1" 200 884
20220802 18:05:14.771 : DEBUG : Remote response: status=200 | data={"value":{"capabilities":{"platform":"LINUX","webStorageEnabled":false,"takesScreenshot":true,"javascriptEnabled":true,"databaseEnabled":false,"networkConnectionEnabled":true,"locationContextEnabled":false,"warnings":{},"desired":{"platformName":"Android","appPackage":"com.cmcc.myhouse.demo","appActivity":"com.cmcc.myhouse.MainActivity","appWaitDuration":60000,"noSign":true},"platformName":"Android","appPackage":"com.cmcc.myhouse.demo","appActivity":"com.cmcc.myhouse.MainActivity","appWaitDuration":60000,"noSign":true,"deviceName":"ed192f0","deviceUDID":"ed192f0","deviceApiLevel":29,"platformVersion":"10","deviceScreenSize":"1080x2160","deviceScreenDensity":380,"deviceModel":"ONEPLUS A5010","deviceManufacturer":"OnePlus","pixelRatio":2.375,"statBarHeight":57,"viewportRect":{"left":0,"top":57,"width":1080,"height":2103}},"sessionId":"312366fe-1008-47f4-9063-1cf0e4a27e0c"}} | headers=HTTPHeaderDict({'X-Powered-By': 'Express', 'Vary': 'X-HTTP-Method-Override', 'Content-Type': 'application/json; charset=utf-8', 'Content-Length': '884', 'ETag': 'W/"374-cX9IxtSKVtVV/oMPHrqcO0PP2Yg"', 'Date': 'Tue, 02 Aug 2022 10:05:14 GMT', 'Connection': 'keep-alive', 'Keep-Alive': 'timeout=600'})
20220802 18:05:14.771 : DEBUG : Finished Request
20220802 18:05:14.774 : FAIL : No application is open
20220802 18:05:14.776 : DEBUG :
Traceback (most recent call last):
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\AppiumLibrary\keywords\keywordgroup.py", line 16, in _run_on_failure_decorator
return method(*args, **kwargs)
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\AppiumLibrary\keywords\_applicationmanagement.py", line 52, in open_application
application = webdriver.Remote(str(remote_url), desired_caps)
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\appium\webdriver\webdriver.py", line 268, in __init__
AppiumConnection(command_executor, keep_alive=keep_alive), desired_capabilities, browser_profile, proxy
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 275, in __init__
self.start_session(capabilities, browser_profile)
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\appium\webdriver\webdriver.py", line 361, in start_session
self.capabilities = response.get('value')
AttributeError: can't set attribute
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\decorator.py", line 232, in fun
return caller(func, *(extras + args), **kw)
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\AppiumLibrary\keywords\keywordgroup.py", line 21, in _run_on_failure_decorator
raise err
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\AppiumLibrary\keywords\keywordgroup.py", line 16, in _run_on_failure_decorator
return method(*args, **kwargs)
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\AppiumLibrary\keywords\_screenshot.py", line 31, in capture_page_screenshot
if hasattr(self._current_application(), 'get_screenshot_as_file'):
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\AppiumLibrary\keywords\_applicationmanagement.py", line 367, in _current_application
raise RuntimeError('No application is open')
RuntimeError: No application is open
20220802 18:05:14.779 : WARN : Keyword 'Capture Page Screenshot' could not be run on failure: No application is open
20220802 18:05:14.780 : FAIL : AttributeError: can't set attribute
20220802 18:05:14.780 : DEBUG :
Traceback (most recent call last):
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\decorator.py", line 232, in fun
return caller(func, *(extras + args), **kw)
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\AppiumLibrary\keywords\keywordgroup.py", line 21, in _run_on_failure_decorator
raise err
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\AppiumLibrary\keywords\keywordgroup.py", line 16, in _run_on_failure_decorator
return method(*args, **kwargs)
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\AppiumLibrary\keywords\_applicationmanagement.py", line 52, in open_application
application = webdriver.Remote(str(remote_url), desired_caps)
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\appium\webdriver\webdriver.py", line 268, in __init__
AppiumConnection(command_executor, keep_alive=keep_alive), desired_capabilities, browser_profile, proxy
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 275, in __init__
self.start_session(capabilities, browser_profile)
File "c:\users\xiangfang\appdata\local\programs\python\python37\lib\site-packages\appium\webdriver\webdriver.py", line 361, in start_session
self.capabilities = response.get('value')
AttributeError: can't set attribute
Ending test: XiriTest.XiriBusinessTest.26MainBusinessTest.2.6CommonCMD

Answer 1

The app is usually opened automatically by Appium and then makes the necessary connections. Tests can fail if the app is already open.
Are you sure the appPackage and appActivity are correct? It would be worth double checking these.