📌 Title:
Warning when attaching to browser causes process to hang
🔍 Description of the Issue
We have a couple of processes using the same VBO that intermittently get stuck in a warning state in Control Room when attempting to attach to a Chrome browser instance. When this occurs, the process does not throw an exception — instead, it hangs indefinitely until a human intervenes by manually closing the browser on the resource PC. Once the browser is closed, the process resumes and continues successfully.
🎯 Expected Behaviour
The process should fail to attach, trigger the retry logic, and then continue execution without requiring manual intervention.
💥 Actual Behaviour
Instead of failing and following the retry loop, the process immediately enters a warning state on the first attempt to attach and does not progress. No exception is thrown.
Errors logged when the issue occurs:
- "ERROR: Internal : Failed to perform step 1 in Navigate Stage 'Attach' on page 'Attach' - Unable to contact the tab. Blue Prism could not establish a connection with the selected tab. This may happen if the tab is in IE Mode or in sleep mode. Please ensure the tab is active and accessible."
- Human intervention: browser manually closed
- "ERROR: Internal : Failed to perform step 1 in Navigate Stage 'Detach' on page 'Init' - Not Connected"
Important:
This process is designed to fail to attach when the tab is unavailable, and normally does so correctly both before and after these occurrences. The abnormal behaviour only happens during this warning hang condition.
🧪 Steps to Reproduce
This issue is intermittent and has no identifiable pattern.
It has occurred 16 times since 09/12/2025, but cannot be reproduced on demand.
⚙️ Technical Details
- Blue Prism Version: 7.4.1
- Operating System (resource PC): Windows 11 Enterprise 24H2
- OS Build: 26100.3194
- Installed: 09/05/2025
- Target Application: Chrome browser version 143.0.7499.148
- Execution Method: Running from Control Room
- Other Notes:
- Issue consistently occurs during the “Attach” stage
- Process remains in a warning state instead of erroring
- Browser / tab state appears to be a factor
🧩 Troubleshooting Attempted
- Broadened the tab-selection logic using a collection of possible tab names
- Reviewed attach parameters
- Verified correct Chrome profile and extensions installed
- Ensured the page is fully loaded before attach attempts
- Issue still occurs intermittently
❓ Additional Context
- The process has run reliably for several years; the issue first appeared on 09/12/2025.
- An identical VBO running in a separate environment has not experienced the issue (Chrome version on that environment is currently unknown).
Any insight or suggestions would be gratefully accepted and considered.
