Power Platform Community Forum Thread Details

Barcode reader - automatically scan

Hi everyone,

I'm working with the Barcode Reader control in a Canvas App using the "Automatically Scan" feature. Sometimes, the scanner registers the same QR code twice, in some cases, the app crashes, forcing the user out.

We've set the Scan Quality (qcan) to "High" because lowering it seems to increase the frequency of crashes. However, we are unsure if this setting is directly related to the issue.

Is there a way to reduce app crashes? Also, is it possible to set a limit of one scan per QR code to avoid unintended duplicates?

Any insights or best practices would be greatly appreciated!

Thanks in advance!

Categories:

Power Apps portals

@PD-08011026-0

You're encountering a common issue with the Barcode Reader control in Power Apps, especially when using the "Automatically Scan" mode. Here's a breakdown of the problem and some practical solutions:

🔍 Problem Summary

Duplicate scans: The scanner sometimes registers the same QR code more than once.
App crashes: Especially when scan quality is set to lower levels.
Scan Quality (qcan): Setting it to "High" improves stability but doesn't eliminate the issue.

✅ Recommendations & Best Practices
1. Debounce the Scan Event
Use a variable to temporarily disable scanning after a successful scan:

// OnScan property of the Barcode Reader

If(

!varScanInProgress,

Set(varScanInProgress, true);

Collect(ScannedCodes, BarcodeReader1.Value);

// Optional: Add logic to check for duplicates

Set(varScanInProgress, false)

)

Or introduce a timer to delay reactivation of the scanner.
2. Prevent Duplicate Scans
Before adding a scanned value to your collection, check if it already exists:

If(

!IsBlank(BarcodeReader1.Value) &&

!IsMatch(BarcodeReader1.Value, Concat(ScannedCodes, Value & "|")),

Collect(ScannedCodes, {Value: BarcodeReader1.Value})

)

3. Use “Select to Scan” Mode Instead
If stability is more important than speed, switch from Automatically Scan to Select to Scan mode. This gives users more control and reduces the chance of duplicate triggers.
4. Test Across Devices
Some crashes may be device-specific. If possible, test on different models and OS versions to isolate the issue.
5. Log and Monitor Crashes
Use Power Apps Monitor or Azure Application Insights to track when and why crashes occur.

⚠️ Known Limitations

The Automatically Scan mode is more prone to rapid re-triggers.
The Scan Quality setting affects performance and stability but doesn't control scan frequency.

🏷️ Tag me if you have any further questions or if the issue persists.

✅ Click "Accept as Solution" if my post helped resolve your issue—it helps others facing similar problems.

❤️ Give it a Like if you found the approach useful in any way.

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