raise UaStatusCodeError(self.value) asyncua.ua.uaerrors._auto.BadSessionNotActivated: "The session cannot be used because ActivateSession has not been called."(BadSessionNotActivated)

[jeffrey-meyer]

???

[AndreasHeine]

details? 🤣

[jeffrey-meyer]

that's the error I get when trying to connect to opc ua server, on a codesys softplc running on a vm

[AndreasHeine]

looks like you perform a session transaction before the client has completed to connect!?

usually first socket connect then send hello then secure channel then crate session then activate session then ... read/write ...

opcua-asyncio/asyncua/client/client.py

Line 269 in d5bacbc

async def connect(self):

    async def connect(self):
        """
        High level method
        Connect, create and activate session
        """
        _logger.info("connect")
        await self.connect_socket()
        try:
            await self.send_hello()
            await self.open_secure_channel()
            try:
                await self.create_session()
                try:
                    await self.activate_session(username=self._username, password=self._password, certificate=self.user_certificate)
                except Exception:
                    # clean up session
                    await self.close_session()
                    raise
            except Exception:
                # clean up secure channel
                await self.close_secure_channel()
                raise
        except Exception:
            # clean up open socket
            self.disconnect_socket()
            raise

can you provide a code sniped and show how you use the client?

[YiannisTsitouridis]

Good day all,
Dear @jeffrey-meyer, I have the exact same problem when trying to connect with a WAGO PLC programmable with Codesys, although I never had this error before with other servers of any kind.
What I initially thought is that the problem occurs when the WAGO device asks the server asks for the user credentials from the client. I understood that when I tried to connect to the WAGO opcua server with the UAExpert Client and a window popped up asking for username and password. However, I haven't found a way to disable this option through Codesys menu yet and to connect only with url.
I am really curious to see if you solved your problem and if @AndreasHeine 's solution was helpful to you.

[schroeder-]

You need to set the password user before connecting:

client = Client(....)
client.set_user('xxx')
client.set_password('xxx')
async with client:
      ....

[YiannisTsitouridis]

Thank you very much, actually I was looking for a way to avoid this option though for using in a system with multiple similar servers.
So I was wondering if there was a way to avoid this option on the server side.
But anyway, I will probably use this one if I cannot avoid credentials.
Again thank you for your help.

[jmtatsch]

Have seen the same error when updating python from 3.9 -> 3.11.
It went away when using the latest asyncua==1.0.5 fortunately