QR Code Scanning Problems - How to Fix Unreadable QR Codes

Shahla Abdulova

Jun 12, 2024

4 min read

QR code scanning problems

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Unreadable QR codes often result from issues such as low contrast with the background, blurriness or pixelation due to low-resolution printing, and incorrect sizing that makes details hard to scan. Physical damage like rips or smudges, poor lighting conditions causing glare or shadows, and insufficient border space are able to hinder scanning. Device-related QR code scanning problems like dirty lenses or software glitches, broken links, overloaded codes, expired codes, and poor placement further contribute to scanning failures. The following factors often resolve the problem if a QR code won't scan. Ensure high contrast between the code and its background to fix a QR code. Print at high resolution and use vector formats to avoid blurriness. Make sure the code is at least 2x2 cm for readability. Protect the code from physical damage and ensure it has sufficient border space. Use proper lighting to avoid glare and shadows. Try different scanner apps, like Google Lens, if the built-in app fails. Regularly check that linked URLs are active and use URL shorteners for easy updates.

Color Contrast

QR codes require a significant contrast between the squares (data modules) and the background to be scanned successfully. The scanner is not distinguish the QR code from its surroundings if the foreground and background QR colors are too similar. Scanning issue often arises when light-colored codes are placed on light backgrounds or dark codes on dark backgrounds, causing the code to blend in and become unreadable.

Blurry Code

Blurry Code

A blurry or pixelated QR code prevents accurate scanning. A blurry QR code issue typically occurs when the QR code is printed at a low resolution, making the edges of the squares indistinct and the patterns unclear. Resizing a QR code without maintaining its quality leads to pixelation, further complicating the scanner’s ability to read the code accurately.

Size

Size

The size of a QR code is critical for successful scanning. QR codes that are too small do not contain enough detail for the scanner to interpret the encoded information. The scanner needs to capture all the individual squares within the code, and if the QR code is undersized, it is impossible to distinguish these squares correctly, resulting in scanning failures.

Damage

Physical damage to a QR code significantly impairs its readability. Common forms of damage include rips, scratches, smudges, or wear and tear, which can impact the pattern of squares. Even minor damage disrupts the alignment and arrangement of the squares, making it difficult for scanners to decode the information accurately.

Lighting

Lighting

Proper lighting is essential for QR code scanning. Insufficient lighting makes scanning hard for the camera to detect the QR code, while overly bright light causes glare, reflecting off the surface and obscuring the code. Both scenarios create challenges for the scanner, which relies on clear visibility to process the code’s pattern.

Border Space

Border Space

QR codes need sufficient quiet zone or white space around their borders to be correctly scanned. The scanner is unable to distinguish the QR code from its surroundings if there is not enough space around the border. The quiet zone acts as a buffer, helping the scanner to recognize the start and end of the QR code.

Device

The problem with scanning QR codes is able to be related to the device’s camera. Issues such as a dirty lens, camera hardware defects, or software errors affect the camera’s ability to focus and capture the QR code clearly, and the phone not scanning QR code issues occur. It is able to be difficult to read codes accurately even if there is a slight malfunction.

QR codes often link to online content, and if the destination website or file no longer exists, the user encounters a broken link or a 404 error. A broken link issue arises not from the scanning process itself but from the QR code directing to a non-existent or moved URL, rendering the code ineffective in providing the intended information.

Overloaded Code

Overloaded Code

QR codes have a finite capacity for storing information. Overloading a QR code with too much data leads to overly complex patterns that are difficult for scanners to decode. This complexity reduces the code’s size and the individual square’s clarity, making it challenging for the scanner to interpret the encoded information accurately.

Expired QR Code

Some QR codes are time-sensitive and have an expiration date, after which they no longer function. An expired QR code does not direct the user to the intended content or service, leading to frustration and failed access. An expired QR code is widespread in promotional materials, event tickets, and time-limited offers.

Wrong QR Code Placement

The placement of the QR code plays a crucial role in its scalability. QR codes are difficult to scan when placed on curved surfaces, in hard-to-reach areas, or where other objects cover them. Placing QR codes in locations vulnerable to glare or shadowing also prevents successful scanning.

How to Fix a QR Code

To fix a broken QR code, try to follow the steps given below.


1. Ensure Contrast

A well-defined QR code requires a high contrast between the squares (data modules) and the background for successful scanning. The most effective QR codes typically feature dark squares on a light background, providing the best contrast and making the individual squares easily distinguishable. Poor contrast, such as light-colored squares on a light background or dark squares on a dark background, makes it difficult for the scanner to differentiate the code from its surroundings, leading to scanning failures.


2. Check Clarity

Printing QR codes at a high resolution is crucial to avoid issues with blurry or broken QR codes. High-resolution printing ensures that the edges of the squares are sharp and well-defined, making it easier for scanners to read the code accurately. Maintain the QR code’s quality using vector-based formats like SVG that do not lose clarity when scaled when resizing a QR code. Avoid using low-resolution images that become pixelated when enlarged. Choose raster formats like PNG for digital use.


3. Verify Size

QR codes must be printed appropriately, allowing the scanner to capture all necessary details to ensure successful scanning. Avoid printing QR codes that are too small, small sizes make the individual squares within the code difficult to read. QR codes must be at least 2x2 cm. Always test the QR codes at their intended size and distance to ensure they are easily scannable.


4. Inspect for Damage

It is essential to protect QR codes from physical damage to maintain readability. Use durable materials and lamination to shield the QR code from rips, scratches, smudges, and wear and tear. Place the QR codes in areas where they are less likely to be handled roughly or exposed to elements that could cause damage.


5. Adjust Lighting

Ensure uniform lighting in the display environment prevents glares and shadows on the QR code. Test the QR code in different lighting conditions to identify potential QR code scanning problems if the environment's lighting is not able to be controlled. Experiment with various screen brightness levels for digital displays to determine the most suitable one for clear scanning. Use different QR code reader apps and devices to assess the ease of decoding. Advise the audience to use phone cameras or apps with built-in flashlights in dimly lit areas, like clubs, if can't scan QR code issues arise.


6. Ensure Adequate Border Space

Make sure always to leave enough space for the quiet zone around the QR code. The ideal size for the quiet zone is to be, at minimum, four times larger than the width of the QR code modules. The modules are the individual squares that make up the QR code in black or other colors if the QR code is customized. The QR code module size decreases as more data is added, but the quiet zone area must not be reduced. Maintaining a proper quiet zone ensures the scanner can accurately detect and read the QR code, improving scalability and reducing errors.



7. Try Different Scanner App

Using a different application is necessary if the built-in camera app fails to read QR codes. Download a dedicated third-party QR code scanner app from the Google Play Store or App Store if the phone won't scan the QR code. Third-party QR code scanner apps are often optimized for a broader range of QR codes and scanning scenarios, increasing the chances of successful scans. Consider using Google Lens for QR scanning, as it is known for its effectiveness in various conditions.


8. Test Link

Verify the URLs linked to QR codes are active and valid to prevent broken links. Check the URL by routinely testing the QR codes to ensure they lead to the correct web pages. Consider using a URL shortener service that allows the destination URL to be updated without changing the QR code.


9. Prevent Overloaded Code

Optimize the amount of data encoded to avoid overloading the QR code. Use URL shorteners to reduce the length of URLs before embedding them in the QR code. Consider creating multiple QR codes, each containing a portion of the data or linking to a webpage that hosts the additional information. Ensure the encoded data remains within the capacity limits of the QR code version, which helps maintain clarity and scalability.


10. Check the QR Code’s Expire Date

Manage time-sensitive QR codes and ensure users know their expiration date on printed materials or displays. Monitor and update the content regularly to ensure it remains accessible until expiration. Consider using dynamic QR codes for events or promotions updated with new information or redirected to new URLs after the initial content expires. Considering expire date ensures users always have access to relevant and current information.


11. Place QR Codes Carefully

Place QR codes on flat, smooth surfaces that are easily accessible and visible to users. Avoid putting QR codes on curved or textured surfaces that distort the pattern. Ensure the QR codes are comfortable and within the line of sight, making it easy for users to scan them without needing to reach or bend awkwardly. Avoid locations with excessive glare or shadows that obscure the QR code, and consider the lighting conditions in the area to ensure the QR code is well-lit but not reflective.

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What if the QR Code is Damaged?

If a QR code is damaged, it is still scannable due to built-in error correction features. QR codes incorporate redundancy, meaning some data is repeated throughout the code. The redundancy feature allows scanners to correct for a certain amount of damage, such as small tears, scratches, or dirt. The level of error correction determines how much damage is able to be tolerated when the QR code scan not working problem occurs.


  • Low (Level L): Recovers around 7% of errors.
  • Medium (Level M): Recovers around 15% of errors.
  • High (Level Q): Recovers around 25% of errors.
  • Best (Level H): Recovers around 30% of errors.


Try adjusting the lighting and angle, zooming in with the phone's camera, or using a QR scanner app with more advanced error correction capabilities to recover a scan from a damaged QR code.

The Importance of Scanning the QR Code for Testing

Testing QR codes before widespread use is crucial to ensure they function correctly and provide a seamless user experience. QR codes are rigorously tested to identify QR code not scanning problems and correct them early, preventing user frustration and protecting the credibility of the brand or organization. Effective testing verifies the QR code's accuracy, readability, and overall functionality, ensuring it performs as expected in various real-world scenarios. The 6 benefits of scanning QR codes for testing are listed below.


  • Confirms the QR code directs users to the correct destination.
  • Ensures the QR code is straightforward and easily scanned by different devices.
  • Identifies errors in the code’s creation or data encoding and fixes the QR code.
  • Catches issues early to avoid user dissatisfaction.
  • Guarantees the QR code leads to the expected result smoothly.
  • Allows for prompt fixes before the QR code is widely distributed.
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Content Manager

Shahla Abdulova

Shahla Abdulova is the dynamic content manager at QR Code Creator, where her creativity and intelligence shine through in every project. Renowned for her SEO-friendly blogs, Shahla crafts content that not only engages but also ranks. Outside of work, she immerses herself in the arts, finding joy in drawing and reading. Her unique blend of skills and passions makes her an invaluable asset to her team and a constant source of fresh, innovative ideas. Shahla's dedication to her craft is truly inspiring, making her a standout in her field.

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