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Error Troubleshooting

The loading bar keeps spinning when capturing images with iPhone.


iOS 16.4 was released on March 27th, 2023. In this version, all browsers on iOS have begun to support OffscreenCanvas. Unfortunately, Apple’s implementation of the API is still incomplete and is missing an important feature: “webgl context”. Please see the MDN docs on OffscreenCanvas for more details.


OffscreenCanvas is utilized in all versions of the Dynamic Web TWAIN Mobile Web Capture Edition. After you upgrade your iOS to v16.4, the loading bar will keep spinning when you try to capture an image. Note that the Service Edition is not affected by this issue.


Add the following lines of code to disable the API.

if (Dynamsoft.navInfoSync.biPhone || Dynamsoft.navInfoSync.biPad) {
    window.OffscreenCanvas = null

Or download the patch version:

  • For NPM project, please upgrade your dwt package to v17.3.4 or v18.0.2.

  • For Non-NPM application, please download the new camera.js file below and replace the old file with new one under Resource/addon directory.

If the resolution doesn’t work for you, please contact us.

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