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

[jmgbwxt]

Good day, everyone.
I too have been receiving this error message however, only when I attempt to use user credentials. Otherwise, I am able to connect and activate session. When I set the credentials- like how @schroeder suggested, and look at Debug level logs- the connect() method will reach await.create_session() and traceback shows the create_session sending from the UASocketProtocol. I get the CreateSessionResponse as well as the find_endpoint INFO log. The difference in the traceback occurs right after the WARNING: asyncua.client.client: Requested session timeout to be 3600000ms, got 100000ms instead. When I use creds the next INFO: is the UAClient calling close_session, when I don't use creds the next INFO: is the UAClient calling activate_session. I can add the actual traceback(s) if needed later...
What confuses me is that I am connected to two other OPC UA servers using creds and they both reach "Sending plain-text password" and connect/disconnect properly.

[schroeder-]

Looks like the length field is missing see https://reference.opcfoundation.org/Core/Part4/v104/docs/7.36.2.2#_Ref482553831 . Strange that it works most of the time.

[AndreasHeine]

Looks like the length field is missing see https://reference.opcfoundation.org/Core/Part4/v104/docs/7.36.2.2#_Ref482553831 . Strange that it works most of the time.

i am confused as well!!!

edit:
i guess its an asyncua Client and Server issue because the test did not fail!
https://github.com/FreeOpcUa/opcua-asyncio/blob/master/tests/test_password.py

[Statkern15]

Hi!
Are there any updated on how to resolve this issue?
I'm running into the same BadSessionNotActivated issue on one machine. The Basic128Rsa15 security policy is enabled on the server.
Thanks in advance!

[schroeder-]

My best quess is to set a certificate could help.

[Statkern15]

Thanks for the fast reply. Do you mean something like:

await client.set_security(
        SecurityPolicyBasic256Sha256,
        certificate=str(cert),
        private_key=str(private_key),
        server_certificate="certificate-example.der",
    )

because i am already doing that ...