A few years ago, Bruce Armstrong kindly provided me with PBL to implement two-factor authentication. I implemented it then in my application, and it worked for several years without any problems. What's more, it still works for existing users who had already connected their IPhones to Google Authenticator using a QR code that they scanned when they first logged in.

However, today a new user was unable to do so because the QR Code Picture control was not populated with the QR code. I analyzed why this happened and found that URL returned by the GenerateProvisioningImage() function of the NVO u_google_authenticator (i.e., https://chart.apis.google.com/chart?cht=qr&chs=400x400&chl=otpauth%3A%2F%2Ftotp%2FSEPTA%3Agm%3Fsecret%3DMYYDSRKSGM2XGOLVKI2FUUC2LBUDCZCB) gives 404 error with message "The requested URL/chart was not found on this server. That's all we know." The second returned parameter of GenerateProvisioningImage() function "response" is empty string.

The last new user registered about 2 months ago and had no problems.

Do you know if Google has changed anything on their side? And how can I get my two-factor authentication working properly again?

Thank you,

George