Troubleshooting Common Scan Problems

Barcodes are crucial for supply chains, logistics and for product identification.

Do you sometimes have trouble reading a bar code with your scanner? It could be something simple, like holding the scanner incorrectly, or mounting it at an incorrect angle, or maybe your scanner isn’t configured for the symbology you’re trying to read. What follows are some tips for solving common bar code scanning issues.

 User Error

Sometimes the way the barcode is oriented to the scanner prevents a successful scan. In this case, try the following:

  • Vary the distance and angle between the scanner and the barcode.
  • Focus on scanning one bar code at a time instead of multiple barcodes on a package.
  • Be sure you are scanning the correct barcode if the item is labeled with multiple barcodes.

Scanner Configuration

Be sure the scanner is configured for the type of barcode you want to scan:

  • Laser scanners can only read one dimensional (linear) barcodes like the GS1-128. They cannot read two-dimensional barcodes like the GS1 DataMatrix.
  • Only imager lasers and camera orientation scanners can read 2D barcodes.
  • Make sure the symbology is enabled in the scanner for the barcode you are scanning. Check the minimum and maximum character settings and the scanner settings for that symbology.

Mechanical or Electrical Problems

Maybe the scanner is not working correctly due to some mechanical or electrical issue:

  • Check the battery status. If there is less than 50% of the battery life remaining, change (or recharge) the battery and try again.
  • Verify that the scanner is securely plugged into the outlet. Also check the cord for wear or breaks, as this can interfere with proper scan operation.
  • Ensure that the scanner lens is clean. Smudges, fingerprints, or dust can impede scanning. Try wiping the scanner lens with a soft lens cloth.
  • Check if the scanner lens is scratched or damaged in any way. If so, it will need to be serviced.

Bar Code Print Issues

Sometimes it’s not the scanner that is the problem. The barcode itself might not have been printed correctly. Following are some problems that can happen when printing barcodes:

  • All barcode fonts require a special start character, a stop character, and most require a calculated check digit. Make sure the required format is being used to print the barcode fonts.
  • Try printing the barcode font at different point sizes. Not all barcode scanners are the same; some lack the ability to scan all types and sizes of barcodes. Some scanners have a narrow reading width and cannot read long barcodes, while others cannot read small barcodes.
  • If the barcode appears to be truncated, increase the height and width of the field the font is displayed in so there is extra white space before and after the resulting barcode. Most barcodes require a white space around the printed symbol that is at least 10 times the most narrow bar in the barcode.
  • Check the print quality and DPI of the printer. Thermal printers that are 203 dpi or less can produce poor quality bar codes.
  • Make sure the material the barcode is printed on has proper contrast. Normally, the barcode should be black and the background white. Using other colors might cause poor scanning conditions. Also, make sure the material is not too glossy or the scanner light may reflect and not properly read the barcode.

Generally, if there is a barcode reading problem, it represents a failure at some point. A failure to print high-quality barcodes; a failure to specify the correct specification scanners or install them properly; failure to set up barcode scanners. If the barcodes you print are being used in your customer’s supply chain, it is hugely important that your printing is correct and to the required quality. See our article on Printing the Best Quality Barcodes to learn more.

Having problems with GS1 barcodes? Check out the ID Technology Guide to GS1 Barcodes.

 Do you want to get started improving your barcode printing and scanning?  Contact us today – 888-438-3242 Option#3 or you can contact me directly at We’ll get you in touch with one of our specialists right in your area.

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  1. Hi David,

    Very impressed with your support on this thread. I am wondering if you can offer some input for my situation. I had a functional setup (receipt printer, program, scanner), but the printer’s hardware was malfunctioning. So we have just ordered two Epson TM-T88V-i receipt printers. Now barcodes printed (through a library system Voyager – Exlibris) are not scanning (Honeywell Eclipse ms5145). Other barcodes printed outside of the program do scan. The program (I believe) does not have any settings that can change for the barcode, and also shouldn’t be changing due to the change of a printer. The scanner is also defaulted to scan several different types barcodes. This issue also is on multiple machines, not just local to one. Overall, the only thing replaced was the receipt printer. The scanner and program worked with the old printers. Can printers change the format of a barcode (symbology or any other reason that would stop if from scanning)? The printer should just be transferring data, not altering it. I understand that all signs lead to the program. But I would greatly appreciate the advice from an experienced barcode perspective.

    Thank you very much, I appreciate any help.


  2. David Holliday says:

    Hi Brandon, if you could send an image of both the old and new barcodes I’d be happy to take a look and see what has changed.

  3. I am trying to use a scanner to scan in long reference numbers when receiving raw materials. The scanner reads the barcode just fine, the problem is the page is filled with barcodes and the scanner often gets the wrong one. Any simple solutions to this issue? We thought of making a template with a slot in it to move around the page but that seems a bit cumbersome. Thanks for any insight!

  4. David Holliday says:

    Hi Mike,
    Yes, this can be an annoying problem.
    One solution is to use a scanner with an aiming dot – with this, you can make sure the scanner is aimed at the correct barcode on the sheet – this greatly increases the chance of reading the correct one.
    Most of the barcode scanner companies have models with this feature – yours might already have it and it just needs to be turned on.
    In the past, I’ve had to resort to making a little sheet metal shield to fit over the scanner to reduce the field of view to deal with the problem as well.

  5. My scanner worked once after I configured it but now it will either NOT turn on AT ALL even though it’s a USB or it beeps red on the top right blinker every 10 seconds. Any ideas on what the problem is?

  6. David Holliday says:

    Hard to say without more info, Bree. Do you have the manual for your particular scanner (or find it online) so you can see what that flashing led indicates? You might want to try a different USB port as well.

  7. Re Printer MG3550. My battary ran out then I plugged in the cable in the socket. The scanner keeps loading and cannot get scanner working

  8. From Julian Borg Re Printer MG3550, My laptop battary ran out while trying to scan a picture. I quickly plugged in eletrical cord but scanner will not work, keeps loading and that it, Thanks

  9. David Holliday says:

    I’m not familiar with that printer, sorry Julian.

  10. HI SIR.
    I have two hand scanners of Honeywell i make the barcode my self of the company that i work in, my issue is that the scanners reed some of printed lables and does not read others , i called the accouning programer to answer this issue .. he changed some of sittings in the program then the new lables is checked normally , how can i scan thousands of my products that i had pasted the lables does not matched with scanner???

  11. David Holliday says:

    Maybe your scanner is set to only read the original type of barcode. In the manual, there is usually a setting barcode you can scan to set back to defaults. Doing that might help you.

  12. I have a printed ticket and i was wondering if a mobile device would interfere with the barcode in any way? Thanks

  13. Martin Clark says:

    Hi David,
    Thank you for a very useful thread.
    Our local horticultural society, run completely be volunteers, uses a Datalogic Heron D130 scanner with a Geller SX-690 terminal/till. On occasions, when scanning a bar code, 2 or 3 entries appear on the purchased items following a single scan. This happens rarely but with a range of operators.
    I have followed your advice regarding cleaning the scanner window and also checking the USB cable and connecting. No issues have been found.
    Could you advise if this might be a problem with the scanner or with the terminal/till?
    Have you heard of this type of problem before and is there any solution for it?

  14. David Holliday says:

    Hi Martin,
    I suspect this might be a scanner issue. Are you using it in the stand so that is scans automatically or handheld where the operator uses the trigger? In either case, it might be that the scanner is allowing more than one scan in a short time period. You should be able to adjust this using the Datalogic setting utility.
    You’ll find more details in the Datalogic manual – Pt No: 90ACC1877 I don’t believe this is on the Datalogic site, but you might be able to find online somewhere.

  15. David Holliday says:

    It shouldn’t.

  16. Dhronal Shah says:

    Hi David,
    I’ve Motorola LS2208 scanner that we use to scan our products that have code 128 Auto barcodes. When I use this scanner it gives different results each time. Our barcodes are alphanumeric – first 3 being letters and next 4 being numbers. With each scan the letter keep on changing from upper to lower case. Can you help?

  17. David Holliday says:

    Hi Dhronal – usually if the scanner is changing the case of the characters it is often caused by the caps lock key being activated on the computer you are scanning into.

  18. Dominic K. says:

    I could really use some help.

    My job at the company I work for is managing all the handhelds and things pertaining to them. Once in a while I will get an issue where we will get a barcode that we can’t scan. So far I have been able to muscle my way through them. I am in the position I am in because I had the most experience with the handhelds which was almost none. Everything I know has been learned by trial and error so it has been interesting at times. Anyway…I have another one of these situations and I am STUMPED. Basically we need to scan thousands of HP laptops that are not in their box. The serial number is on the bottom and is almost impossible to scan. After a lot of moving the beam around, you might be able to get it to scan, but I have never been able to scan it with any ease. Right now we have people with magnifying glasses manually entering these serial numbers and everyone is looking at me. I downloaded a couple apps on my phone. When it does scan, it shows as a Code 128. However, on 1 of the apps, once in a while it scans as an EAN_8, but the numbers that it shows are no where to be fund on the laptop. I have tried multiple Zebra, Motorola and Symbol scanners. I have tried everything I can get my hands on and every time it is the same thing. I have disabled all symbology besides Code 128 and I can scan every Code 128 barcodes with ease besides this one. The kicker is that HP and other companies they have contracted have been able to scan these, but I am unable to find out how or with what. I have tried adjusting the max and min length under Code 128 as well…I can’t get it to scan any better than it does. I’d be happy to provide pictures, etc….anything that you need. My gut says the contrast isn’t different enough between the back ground and fore ground. I would think there would be some sort of setting that can be changed to accommodate that though to a degree. Even still, others are able to scan this normally. The main device I am using is a Zebra MC92N0 with Wavelink’s Terminal Emulation Client v7.3.


  19. David Holliday says:

    Hi Dominic,
    It’s hard to know what’s going on – you are welcome to send me a photo of some of your barcodes.
    Those small serial number barcodes can be tricky to read and I’ve found they are not always printed particularly well.
    The MC9200 series of mobile computers comes with several choices of scan heads – I believe one is designed especially for small high-density barcodes. If you are not already using this, it might be a good upgrade for your application.

  20. Gareth Darby says:

    We have DT039-50 wristband printers that print a 2D barcodes. They will print fine as a local administrator but garbled when logged in as a standard user. Any ideas?

  21. David Holliday says:

    Hi Gareth, I believe that printer is made by Zebra. Your best bet would probably be to contact Zebra support or your local Zebra distributor.

  22. Hey there,
    I am using datalogic suic scan lite scanner / qw2100 model.
    When I am trying to scan a USPS barcode. its shows more numbers in front, like:
    But on the label tracking numbers are starting from 9405515902079906012105, same problem with FedEx Ground barcodes.
    ]C142019703 from here 19703 is my postal code.
    and I dont have a problem scanning UPS barcodes.
    Do you know what kind of mode I have to select for solving above described problem.
    Thanks in advance!

  23. David Holliday says:

    Hi Narek,
    I believe the US and Fedex barcodes contain some non-printing characters that your scanner is not able to parse correctly. I don’t know how you would set up a Datalogic scanner to read these – Datalogic tech supposrt might be your best option.

  24. Hi David. I have Honeywell MS7120 Orbital scanners on two point of sale terminals. They are both setup identical but one scanner does not read about 6-10 items. The other scanner reads all of the items. When I switch the scanners with one another the problem follows the scanner. Just certain items do not scan, but it shows on the screen that it cannot find the items by the barcode number, but the same item scans on the other scanner next to it without any issue. I have replaced the scanner with a brand new scanner and set it up but have the same issue. any advise you can give me regarding this problem would be greatly appreciated. Thanks

  25. David Holliday says:

    That’s an interesting issue.
    I usually try connecting the scanner to a computer and scan into Notepad. This will show the data the scanner is sending and might give you an idea as to what is happening.

  26. Cody Chwaszczewski says:

    Hey there. We have an LS2208 that was working just fine for scanning our inventory. It had a nice long beam length for scanning our barcodes and all was going well until all of the sudden the beam size went from a line down just to a small dot which is no good because we need to scan these barcodes. Is there anyway to switch it back or is the scanner useless now?

  27. David Holliday says:

    Hi Cody, yes the LS2208 is a good little scanner. The laser is basically a single dot that is moved side to side very quickly by a little stepper motor. It sounds as though this has stopped working with yours. If you have a warranty or service plan, you can send to Zebra for repair. Otherwise, it would probably be more cost effective to just buy a replacement.

  28. Jordan Taylor says:


    Great article! I have a peculiar problem with my scanner, Esky ESO14 2.4G Wireless scanner, I am attempting to read barcode labels printed from AutoCad. The quality seems to be fine, but it will read every other barcode I try except the one that we print on our labels.

    I even tried going to the barcode setup and altering the sizes, but this didn’t make a difference. I also went into the print preview, which gives a sample barcode, and it reads that one. But when the information is actually coded into the barcode, it will not read that. Could I possibly send you the file I am trying to read to see if you know what could potentially be the issue?

  29. David Holliday says:

    Sorry for the slow reply – sure, you can send me the file to

  30. Hello,
    We currently use Intermec CK71’s. I have 2 hand held units that will scan in test but not otherwise. We’ve double checked settings and can find no issues. Any ideas?

  31. David Holliday says:

    Hi Mary, if you can scan using the Intermec test app, but not in the actual application you need to use, there is usually that has been missed. Your best bet would be to get in touch with Intermec (Honeywell) support of the company who’s application you are using.

  32. Our shop recently had very bright led lights installed and now are having trouble with our Symbol hand held scanners. Any ideas.

  33. David Holliday says:

    Unless your new lights are causing a lot of reflection on your barcodes, I wouldn’t have thought this would be a problem, Mick.

  34. Our facility has also recently installed new L.E.D. lights and we are starting to get work orders saying the hand held bar code scanners are not working, we move them to an area with the tradional fluorescent lights and the bar code scanners work normally. What causes this ?

  35. David Holliday says:

    Hi Dave, I’ve heard of that happening before. I’m not aware of a solution other than maybe switching to a different type of scanner.

  36. Lisa Ohland says:

    I have a Symbol LS4208 and need to scan a 12 digit barcode into a database. Whenever I scan a barcode, it’s putting an * before the barcode and leaving off the last (check) digit, putting an * there, as well. Any insight? I have 20,000 barcodes to scan. A different scanner I have works fine but I’d like to be able to use both so 2 people can scan simultaneously. Thanks for any suggestions you may have.

  37. David Holliday says:

    Hi Lisa, for your LS4208, I’d reset the scanner to the factory settings, which should fix your problem. There’s a barcode to scan on page 47 of the product guide that will do this for you.

  38. Muhammad Tahir says:

    i am using a honeywell orbit scanner, which do’es not scan QR barcodes. is it ok.

  39. David Holliday says:

    Hi Muhammad, I believe the Orbit scanners are designed to only read linear barcodes so won’t work with the 2d codes like QR.

  40. Hi. I am using a DS6708 to scan Interleaved 2 of 5 codes (with the Any Length parameter). The codes have 14 characters. If I use the scanner in USB – HID keyboard mode, the codes are scanned correctly, but if i switch to CDC COM Port Emulation (which i actually need) the scanner only scans the first 13 characters. Is anyone aware of such limitation in this mode?

  41. David Holliday says:

    Is the 14th character a check digit? You can try using the set up barcodes on this page that might help:

  42. It’s not a check digit. I have scanned the ‘Do not transmit I 2 of 5 Check digit’ barcode but it’s still the same. Just scans the first 13 characters and then adds the Enter option i have set as Data suffix (it’s actually a default setting).

  43. David Holliday says:

    Hmm, if #14 isn’t a check digit, I don’t know what is going on. Have you spoken with Zebra/Symbol tech support or with the reseller you bought the scanner from?

  44. Mike Strout says:

    I am having a problem trying to scan on a system that has embedded Linux under the hood. When I navigate to a field and then scan a label, the field is filled to capacity with what looks like underscores. When I move to another field, that field is instantly filled with underscores as well. The only way past the underscores populating is to reboot the device. Any ideas?

  45. David Holliday says:

    That’s a new one to me, Mike.

  46. Hi, Hoping you can help me. At my place of work we have an LS2208 plugged in via usb. the cord was bad on one scanner that was replaced over the weekend. I came in on monday and the scanner that replaced the old one does not ‘beep’ as we scan merchandise. Do I just have to print up the bar code to turn on the ‘beep’ or to turn it up and scan that bar code? or is there more to it? Thank You for any help you can provide.

  47. David Holliday says:

    Hi, you can control the beeps by using the setting barcodes in the user guide: See section 4.

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