400 Bad Request when attempting to insert QR code image for Google Authenticator

Question

I'm trying to set up two-factor authentication with Google Authenticator on my site. I'm able to generate working codes, but when I insert the image URL into the page, I get the following error in Chrome inspector:

GET https://www.google.com/chart?chs=200x200&chld=M|0&cht=qr&chl=otpauth://totp/MyLabel?secret=THESECRET 400 (Bad Request)

The code to generate the QR code:

try
  key = crypto.randomBytes(10).toString('hex')
catch error
  console.log "error generating code: #{error}"
encoded = base32.encode(key)
label = encodeURIComponent "MyLabel"
uri = "otpauth://totp/#{label}?secret=#{encoded}"
url = "https://www.google.com/chart?chs=200x200&chld=M|0&cht=qr&chl=#{uri}"

Client-side jQuery that inserts the image:

img = $("<img>").attr("src", url)
$("#qr_box").html("")
$("#qr_box").append(img)

Which results in the following HTML on the page:

<img src="https://www.google.com/chart?chs=200x200&amp;chld=M|0&amp;cht=qr&amp;chl=otpauth://totp/MyLabel?secret=THESECRET">

The image can be opened in a new tab without a problem. The image is only successfully displayed in my page about 1/10 the time; the other times Chrome gives a 400. Am I missing something obvious here?

Answer 1

For me it worked to change https://www.google.com to https://chart.googleapis.com.