Issue: Update Scale in ScaleModal not working

WebViewer Version: 8.10.0

Please give a brief summary of your issue:
Trying to update the scale in the ScaleModal.
After clicking on the Update Button, it throws an error.

This only happens, after drawing with the CalibrationMeasurementTool.
When updating the values manually it works fine.

See the screenshot below:

Tested it with and without any annotations.

Creating a new one works fine here.

Please describe your issue and provide steps to reproduce it:

  • open the demo page
  • add a new scale and apply it
  • click on this new scale and try to update it

Please provide a link to a minimal sample where the issue is reproducible:

Hi @alexander.schulte,

Thanks for reaching out to WebViewer Support! We appreciate this bug report and are able to reproduce on our end. We’ve added this bug ticket to our backlog and will have it looked at in our next sprint. We cannot guarantee when exactly it will be fixed/released, but when it does we will let you know when a fix is available!

Let me know if you have any further questions.

Best Regards,
Adam Sinclair
Software Developer
PDFTron Systems, Inc.

Hi @alexander.schulte ,

The fix should be available in the latest WebViewer v8.11, please try it out. Thanks.


Hi Wanbo, thanks for the update! Alex is currently unavailable but I’m a colleague of his and I just tested this again, both in your measurement tools demo and in our own application after updating our PDFTron dependency there to 8.11.0.

Unfortunately I can still reproduce the issue. To clarify, the steps to reproduce are as follows:

  1. create a scale by using the “calibrate” tool and save it
  2. select the newly created scale by clicking on it in the dropdown menu of available scales
  3. click “calibrate” again to update the scale
  4. click on the “update” button, which still throws a console error and does not update the scale

Step 3 is the important one here—the error only appears when attempting to update the scale via the “calibrate” option. Manually updating the values in the input fields works fine.

Please let me know if I can provide further input. Thanks!


The demo page is not update to 8.11.0 as you can check from the browser console. Also forgot to mention that you need to update to the latest nightly build of v8.11.0. Please try it out.


Oh, good to know about the nightly build, thanks for the info. I’ll test again next week and let you know. :+1: Do you already have a time frame for publishing the final version of 8.11.0 to npm?

There’s no final version, just the initial version and the following nightly build versions. You can find all the versions here.


Okay, but at what point do you publish to npm? Or more specifically, when do changes from nightly builds that come after the initial version of 8.11.0 end up on npm? Will they be part of 8.12.0 instead?

I ask because we use npm as our dependency manager and in order to be able to install all dependencies and build our app in an automated fashion, we need to use the version of PDFTron that’s published to npm. :sweat_smile:

Edit: Sorry, I should have actually checked your link before asking my question. :man_facepalming: I see that’s a list of versions on npm. Thank you, this should be all we need for testing!

Edit 2: Tested with 8.11.0-20230102 and can confirm that the bug is fixed, thanks a lot! Am I correct in assuming that 8.12.0 will be the next stable release to contain this fix?

Correct, but the stable nightly builds for 8.11.0 should also be stable as they should only contain tested small bug fixes on top of the initial 8.11.0 build version.

No worries. Glad to help!


Understood, thanks again for the help! Topic can be closed as far as I’m concerned. :slightly_smiling_face:

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