How do I fix "Can't upload" error?

In Widget v3.12.0+ it’s possible to enable a debug mode. When enabled, the widget will display the actual reason why the upload has failed:

To enable the debugging mode, you can use one of the following options:

  1. The UPLOADCARE_DEBUG_UPLOADS global variable
  1. Widget data attribute data-debug-uploads
<input type="hidden" role="uploadcare-uploader" name="file-upload" data-debug-uploads />
  1. Settings object key debugUploads
const dialog = uploadcare.openDialog(null, {
  debugUploads: true

We strongly advise using the latest version of the widget, but if you can’t upgrade for some reason, and your current version is <3.12.0, follow these steps to debug the error:

Let’s find the cause of the message. We will give you a list of things to check in order to avoid common mistakes our users make:

  • Free plan requires account verification before uploading non-image files. Images include the following extensions: BMP, GIF, JPEG, PNG, PCX, TIFF, TGA, WEBP, MPO. If you are uploading any other file type you will need to attach payment information to your account.

  • Free plan has hard limits on uploads and storage - you can see your remaining upload units and other limits in your dashboard. Once you hit the limit, your uploads are paused for the remainder of the current month.

  • Each of our plans has limits on the sizes of the files. Please check that your file is not exceeding the limits.

  • Check if you are able to upload the file using the widget on our main site Were you able to do that? If not, what does it say?

  • Check the “Signed uploads” option – if you are not sure what it is, just disable it.

  • Sometimes it is convenient to upload a file through the URL. Check that URL is correct and the file is publicly available - you should be able to open the URL using “Incognito mode” of your browser.

Getting additional information

Open “Developer tools” (Ctrl + Shift + C for Chrome) in your browser and you will find a tab with network activity. Repeat your file upload and find the line:


click on it and you’ll further see the reason for the disaster:


If you are receiving error messages not covered in this guide you can always check with our support. Your report should be as detailed as possible – your action sequence, information about the file, console messages, any other information that might help us to know more about your setup.

I’m only getting this error when I try to upload from Safari on my phone, so it’s hard to debug the issue. Do you have any other suggestions? Or could it be related to the image format not supported by my account? I was able to upload from my phone camera to the sample widget with the documentation on my phone.

Hi @eluce, there a few possible reasons for this:

  1. The file exceeds the maximum file size limit on your plan.
  2. The type of the file is not allowed on your plan (e.g. free accounts without a card on file can upload images only).
  3. The file doesn’t pass the validation you set up (e.g. if you have the images-only option enabled and are trying to upload a non-image file).

If this doesn’t help, shoot us a note via, and we’ll take a closer look at this.