[Python] OPC UA Python Client Connection Fails with "BadSecurityPolicyRejected" Despite Using...

Connecting to opc.tcp://172.16.0.1:4844...

C:\Users\Administrator\PycharmProjects\PythonProject1\intro.py:272: RuntimeWarning: coroutine 'Client.set_security_string' was never awaited

client.set_security_string(f"Basic256Sha256,SignAndEncrypt,{cert_path},{key_path}")

RuntimeWarning: Enable tracemalloc to get the object allocation traceback ServiceFault (BadSecurityPolicyRejected, diagnostics: DiagnosticInfo(SymbolicId=None, NamespaceURI=None, Locale=0, LocalizedText=None, AdditionalInfo=None, InnerStatusCode=None, InnerDiagnosticInfo=None))

from server received in response to CreateSessionRequest Error: The security policy does not meet the requirements set by the server.(BadSecurityPolicyRejected)

Updated status of server ID None to 'Not Running'. Inserted action log for Server ID None: Not Running in 172.16.0.1


for server in servers:
endpoint_url = server.EndpointUrl
server_ip = server.ServerIP
print(f"Connecting to {endpoint_url}...")

if not ping_server(server_ip):
print(f"{server_ip} is not reachable.")
update_server_status(cursor, None, "Not Running", server_ip)
continue

try:
# Configure OPC UA client
client = Client(endpoint_url)
client.set_user("DEWA_OPC")
client.set_password("RTeK8QrF9F5G")
client.set_security_string(f"Basic256Sha256,SignAndEncrypt,{cert_path},{key_path}")
await client.connect() # Await the connection
print(f"Connected to OPC UA server at {endpoint_url}")

update_server_status(cursor, None, "Running", server_ip)

cursor.execute("SELECT [TagName] FROM [admin_db].[dbo].[opc_ua_tag_name]")
tag_names = [row.TagName for row in cursor.fetchall()]

root = client.get_root_node()
historical_data_node = client.get_node("ns=2;s=RealTimeData") # Adjust the node as needed

# Continuously fetch real-time data for each tag
for tag_name in tag_names:
await fetch_and_insert_data(tag_name, historical_data_node)

await client.disconnect() # Await disconnection
print("Real-time data fetch cycle completed.")

except Exception as e:
print(f"Error: {e}")
update_server_status(cursor, None, "Not Running", server_ip)

await asyncio.sleep(10) # Wait for 10 seconds before the next cycle

except Exception as e:
print(f"Error in main loop: {e}")


I'm trying to connect to an OPC UA server at opc.tcp://172.16.0.1:4844 using Python and the asyncua library. I want to use a secure connection with the Basic256Sha256 security policy and client certificate authentication.
When I run this, I get the following warning and error that mentioned above.

1. 
   Verified that the server supports Basic256Sha256.
   
   
2. 
   Confirmed that cert_path and key_path point to valid files.
   
   
3. 
   Looked up the error and suspect I may be misusing set_security_string.
   
   How should I correctly use set_security_string() with asyncua in an async context? And what could be causing the BadSecurityPolicyRejected error?
   

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