OSError: [WinError 10013] An attempt was made to access a socket in a way forbidden by its access permissions

Do you use antivirus with on-access protection? If yes, try disabling it.

Check similar thread https://stackoverflow.com/questions/2778840/socket-error-errno-10013-an-attempt-was-made-to-access-a-socket-in-a-way-forb

It runs without a problem outside PyCharm! (From windows command line). I suspect antivirus covers command line as well. 

If I'm not mistaken some antiviruses with on-access scan make exceptions for the default system applications.

How does it go if you run it from the embedded terminal in PyCharm? Does it give you the same error?

Yes, the same error. And I use windows antivirus only,  and turning it off did not solve the problem. 

I had this same issue. Here's how I fixed it:

Open CMD as administrator.

Run netstat -ano | find ":<port>" 

This will show you a list of the processes using that port.

You can then run TASKKILL /F /PID <process id>. The process id is the far right column from the previous command.

Hope this helps

Does anyone have a solution to this please? I get the same, pick a port that's not in use, run it from command line and flask starts fine. Do the same within Pycharm IDE (Shift + F10) and I get

FLASK_APP = server.py
FLASK_ENV = development
FLASK_DEBUG = 0
In folder C:/Users/Russ/src/Sat-Im-Object-Detection/image_store/src
C:\Users\Russ\src\myapp\src\venv\Scripts\python.exe -m flask run
* Serving Flask app 'server.py' (lazy loading)
* Environment: development
* Debug mode: off
Traceback (most recent call last):
File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.9_3.9.2032.0_x64__qbz5n2kfra8p0\lib\runpy.py", line 197, in _run_module_as_main
return _run_code(code, main_globals, None,
File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.9_3.9.2032.0_x64__qbz5n2kfra8p0\lib\runpy.py", line 87, in _run_code
exec(code, run_globals)
File "C:\Users\Russ\src\myapp\src\venv\lib\site-packages\flask\__main__.py", line 3, in <module>
main()
File "C:\Users\Russ\src\myapp\src\venv\lib\site-packages\flask\cli.py", line 990, in main
cli.main(args=sys.argv[1:])
File "C:\Users\Russ\src\myapp\src\venv\lib\site-packages\flask\cli.py", line 596, in main
return super().main(*args, **kwargs)
File "C:\Users\Russ\src\myapp\src\venv\lib\site-packages\click\core.py", line 1062, in main
rv = self.invoke(ctx)
File "C:\Users\Russ\src\myapp\src\venv\lib\site-packages\click\core.py", line 1668, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File "C:\Users\Russ\src\myapp\src\venv\lib\site-packages\click\core.py", line 1404, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "C:\Users\Russ\src\myapp\src\venv\lib\site-packages\click\core.py", line 763, in invoke
return __callback(*args, **kwargs)
File "C:\Users\Russ\src\myapp\src\venv\lib\site-packages\click\decorators.py", line 84, in new_func
return ctx.invoke(f, obj, *args, **kwargs)
File "C:\Users\Russ\src\myapp\src\venv\lib\site-packages\click\core.py", line 763, in invoke
return __callback(*args, **kwargs)
File "C:\Users\Russ\src\myapp\src\venv\lib\site-packages\flask\cli.py", line 849, in run_command
run_simple(
File "C:\Users\Russ\src\myapp\src\venv\lib\site-packages\werkzeug\serving.py", line 1008, in run_simple
inner()
File "C:\Users\Russ\src\myapp\src\venv\lib\site-packages\werkzeug\serving.py", line 948, in inner
srv = make_server(
File "C:\Users\Russ\src\myapp\src\venv\lib\site-packages\werkzeug\serving.py", line 780, in make_server
return ThreadedWSGIServer(
File "C:\Users\Russ\src\myapp\src\venv\lib\site-packages\werkzeug\serving.py", line 686, in __init__
super().__init__(server_address, handler) # type: ignore
File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.9_3.9.2032.0_x64__qbz5n2kfra8p0\lib\socketserver.py", line 452, in __init__
self.server_bind()
File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.9_3.9.2032.0_x64__qbz5n2kfra8p0\lib\http\server.py", line 138, in server_bind
socketserver.TCPServer.server_bind(self)
File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.9_3.9.2032.0_x64__qbz5n2kfra8p0\lib\socketserver.py", line 466, in server_bind
self.socket.bind(self.server_address)
OSError: [WinError 10013] An attempt was made to access a socket in a way forbidden by its access permissions

Process finished with exit code 1