Katalon Recorder Plus Shows “Connection Lost”

[thereajeng]

Hi everyone,

I’m having an issue with Katalon Recorder Plus where it always shows “Connection lost” when I try to start recording on Chrome.

Here’s what I’m experiencing:

• The status shows: Katalon Recorder Plus (Connection lost)

• When I click record, it opens Chrome but doesn’t properly proceed with recording

• The recorded steps only show:

  1. Open Browser

  2. Navigate to URL

  3. Close Browser

• The connection drops immediately after starting

• I also tried switching browsers (Edge and Chrome), but the issue still happens

Has anyone encountered this issue before?
Is this related to browser compatibility, extension permissions, or WebDriver configuration?

Any suggestions or fixes would be really helpful. Thanks

[Elly_Tran]

Hi there, and thanks for posting in the Katalon community!

Working with recording, we encourage you trying Katalon Web Recorder Plus: Katalon Web Recorder Plus | Katalon Docs. Double-checking the steps and configurations might resolve the issue.

If the doc doesn’t help, feel free to provide more details, and a community member will assist you soon. Thanks for being a part of our community!

Best,
Elly Tran

[thereajeng]

Hi,

My issue is that when I try to record a web test, the browser opens and navigates to the URL, but then it automatically closes without continuing the recording. It only records the initial steps (Open Browser → Navigate to URL → Close Browser), and the process stops with a ‘connection lost’ status.

I have already tried several troubleshooting steps, but the issue still cannot be resolved.

[sneha.sajeev]

@thereajeng

Hi,

My issue is that when I try to record a web test, the browser opens and navigates to the URL, but then it automatically closes without continuing the recording. It only records the initial steps (Open Browser → Navigate to URL → Close Browser), and the process stops with a ‘connection lost’ status.

I have already tried several troubleshooting steps, but the issue still cannot be resolved.

@thereajeng Do these 5 first:

1. Close all Chrome windows

2. Remove Katalon Recorder Plus

3. Reinstall it

4. Run Katalon as Administrator

5. Try recording again

[arvind.choudhary]

Thanks for sharing the additional details and screenshot — that really helps.

Based on what you described (browser opens → navigates → immediately closes + “Connection lost”), this is not a normal recording issue, it’s a session handshake failure between Katalon Recorder Plus and the browser.

That’s why you only see:

• Open Browser

• Navigate to URL

• Close Browser

The recorder is losing control right after launching the session.

What’s Actually Happening

When you click record:

1. Recorder tries to inject its script into the browser

2. Connection drops immediately

3. Recorder thinks execution is finished → triggers “Close Browser”

**Most Likely Causes + Fixes

1. Recorder Plus Stability Issue (Very Common)**

This exact behavior is widely seen with Recorder Plus.
Fix→
Switch to the stable version of katalon recorder

2) Chrome Security / Extension Blocking
Modern versions of Chrome can block extension injection silently.

FIX**
Try this:

• Go to chrome://extensions

• Enable:

  • “Allow access to all sites”

  • “Allow in incognito” (for testing)

• Disable “Enhanced Safe Browsing” temporarily (just to test)

3. Conflicting Extensions (Very Important)

If you have:

• Ad blockers

• Security extensions

• Other automation tools

They can kill the connection instantly
Fix
Disable all extensions except Katalon Recorder

1. Restart browser and try again

   4 Corrupted Chrome Profile

This issue often comes from profile-level corruption.

Fix:

• Create a new Chrome profile

• Install only Katalon Recorder

• Test recording

5. Background Process Crash

Sometimes the extension service worker crashes.

Fix:

• Go to chrome://extensions

• Click “Service Worker” (Inspect) for Katalon

• Check if it’s crashing when recording starts

Try some of the fixes, hope this will work for you.

[kazurayam]

@thereajeng

I’m having an issue with Katalon Recorder Plus where it always shows “Connection lost” when I try to start recording on Chrome.

Have you upgraded the WebDriver to the latest?
If not, do as documented as follows:

Upgrade or Downgrade WebDrivers in Katalon Studio | Katalon Docs

[thereajeng]

Despite updating the WebDriver, reinstalling the application, and running it as administrator, the issue still persists. I also observed that it works on some websites but not others. Furthermore, recording on Microsoft Edge may work, but executing the test results in an error.

[thereajeng]

Despite updating the WebDriver, reinstalling the application, and running it as administrator, the issue still persists. I also observed that it works on some websites but not others. Furthermore, recording on Microsoft Edge may work, but executing the test results in an error.

[thereajeng]

It still doesn’t work.

[kazurayam]

@thereajeng

Any suggestions or fixes would be really helpful. Thanks

Please look into the .log file.

View Error log​ - Katalon Help | Katalon Docs

In the file, possibly you will find some Exception recorded which would inform you more what happend.

[dineshh]

can you run the same test on publicly available sites and confirm issue is occuring? Also share the log file if it occurs again

[mamtabankoti4]

Yes, this issue usually happens when the extension is not properly connected to the browser. You can try these simple fixes:

• Remove Katalon Recorder Plus and install it again

• Restart your browser after installing

• Go to extensions and allow all permissions

• Disable other extensions (like ad blockers)

• Try using a new Chrome profile

Most of the time, reinstalling the extension fixes the “Connection lost” problem.

If it still doesn’t work, it could be a browser compatibility issue.

[stevio052002]

1. “Connection Lost” Meaning

“Connection Lost” in Katalon Recorder Plus usually means:

• The extension cannot communicate with the browser or Katalon backend

• Or the recording session crashed / disconnected

This is often caused by browser updates, extension conflicts, or network restrictions.

2. Major Causes of the Problem

A. Browser Compatibility Issues

• New browser updates (especially Chrome) break extensions

• Example: Chrome changes removed extension flags → recorder stopped working

B. Network / Firewall / VPN Blocking

• Corporate networks or VPNs block extension communication

C. Extension Version Mismatch

• Old Katalon Recorder version vs new browser

D. Memory / Performance Problems

• Katalon can become slow or crash under load

E. Extension Conflicts

• Other automation tools (Selenium IDE, ad blockers, etc.)

F. Security Restrictions

• Browser blocking permissions or APIs

3. Step-by-Step Fix (Follow in Order)

Step 1: Restart Everything

1. Close browser completely

2. Reopen browser

3. Reload Katalon Recorder

Step 2: Check Internet Connection

• Disable VPN temporarily

• Switch network (Wi-Fi ↔ mobile hotspot)

Step 3: Update Katalon Recorder

• Remove extension

• Install latest version from store

Many bugs are fixed in updates

Step 4: Update Browser

• Go to browser settings → Update

• Restart after update

Important: Some Chrome versions break recorder features

Step 5: Disable Conflicting Extensions

Turn off:

• Ad blockers

• Selenium IDE

• Automation plugins

Then test again.

Step 6: Clear Browser Cache

• Settings → Privacy → Clear browsing data

• Restart browser

Step 7: Check Browser Permissions

Make sure:

• Extension is enabled

• Allowed in Incognito (if needed)

• Has site access

Step 8: Try Another Browser

If still failing → switch browser (see supported list below)

Step 9: Reinstall Browser (Advanced Fix)

If problem persists:

• Uninstall browser

• Install fresh version

• Reinstall extension

Step 10: Use Stable Version Setup

• Avoid beta browser versions

• Use versions known to work with Katalon

4. Major Browsers Affected

Google Chrome

• MOST affected

• Frequent breaking changes

• Extension flags removed → recorder issues

• Mozilla Firefox

• More stable than Chrome

• Still affected by updates occasionally

Microsoft Edge

• Chromium-based → same issues as Chrome

Opera

• May block scripts or extensions due to security

5. Major Problem Issues (Real-World)

Persistent Disconnections

• Recorder disconnects randomly

Recorder Not Capturing Actions

• Inputs or clicks not recorded

Crashes / Freezes

• Especially with large test cases

Version Conflicts

• Browser vs extension mismatch

Network Restrictions

• Corporate firewall blocks connection

6. Expected Outcomes After Fix

If resolved successfully:

• Stable recording session

• No “Connection Lost” message

• Actions captured correctly

• Tests run smoothly

7. Alternative Solutions (If Problem Persists)

Option 1: Switch Tool

• Selenium IDE

• Cypress

• Playwright

Option 2: Use Katalon Studio Instead

• More stable than browser recorder

Option 3: Use “Chrome for Testing”

• Special version for automation (temporary workaround)

8. Quick Troubleshooting Checklist

• Restart browser

• Update extension

• Update browser

• Disable VPN

• Clear cache

• Try another browser

• Reinstall everything