Issue Summary
Some students may experience pixelated, torn, or partially blank screens when working inside the Ubuntu virtual machine in certain labs (for example, during terminal or desktop interaction). In some cases, the display corruption may worsen when moving the mouse.
This issue may make the Ubuntu desktop difficult to use and can prevent completion of lab tasks.
🔗Related article(s):
Why Do Scroll Bars Appear in My Lab Virtual Machine?
Symptoms
You may notice one or more of the following:
- Parts of the Ubuntu desktop appear blank or white
- Screen sections look pixelated or distorted
- Display artifacts change when moving the mouse
- Terminal works, but the overall desktop appears unstable
- Windows-based portions of the lab work normally, but Ubuntu does not
If you see these behaviors, follow the steps below before submitting a support request.
Step 1: Fully Terminate the Saved Lab Instance
If you are resuming a saved lab session, the issue may persist in that saved state.
- Exit the lab completely.
- Ensure the session is fully terminated (do not resume).
- Launch a brand-new instance of the lab.
- Test the Ubuntu virtual machine again.
Saved sessions preserve the virtual machine state. Launching a fresh instance ensures you are testing a clean environment.
Step 2: Disable Browser Hardware Acceleration
Hardware acceleration can sometimes interfere with HTML5-based remote lab environments.
In Google Chrome:
- Go to Settings
- Select System
- Turn off “Use hardware acceleration when available”
- Restart the browser
- Relaunch the lab
In Mozilla Firefox:
- Go to Settings
- Scroll to Performance
- Uncheck “Use recommended performance settings”
- Disable hardware acceleration
- Restart the browser
- Relaunch the lab
Step 3: Try a Different Browser
If you were using Chrome, try Firefox (or vice versa).
Avoid browsers with heavy extensions enabled.
Step 4: Check for VPN or Managed Network Restrictions
VPNs, proxies, and managed school/work networks can sometimes interfere with remote display rendering.
Before testing again:
- Disconnect from any VPN
- If possible, test from a home network
- If using a work-issued device, try a personal device
Step 5: Confirm Normal Linux Password Behavior
When using commands such as:
sudo apt-get install -y qemu-utils
You will be prompted for a password.
⚠️ Linux does not display characters while typing a password.
This is normal behavior. Even though nothing appears on screen, your keystrokes are being entered.
If the Issue Still Persists
If the Ubuntu desktop remains corrupted after completing all steps above:
Please provide:
- Your browser name and version
- Your operating system
- Whether you tested without a VPN
- Whether you launched a new instance (not a saved session)
- The approximate date and time of your most recent launch
This information will allow support to escalate the issue to the platform team for further investigation.
Additional Notes
- Windows-based lab tasks working normally indicates that the lab environment is provisioning correctly.
- Display instability inside Ubuntu is typically related to browser rendering or host-specific session behavior.
- In rare cases, the issue may be isolated to a specific lab host and may require reassignment by support.
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