Start AgentBrowser manually and confirm the main window is visible, then ask the AI to check http://127.0.0.1:10001/agent/v2/capabilities.
Identify the symptom before retrying.
Copy the error code and client version to speed up support.
Read the actual error in the status bar and restart the service. Then check port conflicts, firewall or security software, and include the X-AgentBrowser-Token from api_token.txt.
Ask the AI to reread page/snapshot; do not reuse an expired elementId. Narrow the scope if the target is not unique.
Use the same Windows user and AgentBrowser data directory. Never delete WebView2 user data while the client is running.
Exit AgentBrowser completely before updating. End remaining background processes in Task Manager and retry.