I was so excited to see these posts. I've been trying to register a device for hours earlier today. The login page was refreshing and I couldn't type two letters in. I spoke to an Amazon rep for about 30 minutes and he had me uninstall and reinstall. No change. After some time, he then told me that they would do an investigation and meanwhile I should try Kindle (cloud).
I found this post and changed from "default" to amazon.ca. Finally, the screen stopped refreshing and allowed me to sign in successfully. It then requires a second sign-in and the result is "Registration failed. Please try again (2)". Over and over. I uninstallled and reinstalled once more and I only receive "Registration failed"
Windows 10 on Inspiron 15 7000 Gaming Laptop, downloaded windows file from Amazon.com. I live in north Florida in the US. Kept having the refresh issue, per the advice here I switched it to .ca and it allowed me to register immediately. Now all my books are downloaded.
I had the same issue, the User name/email field kept refreshing (blinking yellow, erasing anything you type) on the sign in page on the Register your Kindle window.
Switching the registration to amazon.ca on the drop-down menu at the bottom of the window worked for me as well!
BTW, I am registering my Toshiba laptop, running Windows 10 Home vers. 1803. I had already tried uninstalling and reinstalling twice, also tried Running app as Administrator once, but those did not have an affect. And I am in the U.S., not CA.
Having the same Issue switching to amazon.ca does not work... Because the two step authentication fails... Got the refreshing loop issue.. got it to stop by pressing the F5 button for five seconds on the amazon.com login. However the page refreshes on the two-step authentication and can not enter pin number. Can anyone please help!
I installed Kindle for PC and was baffled to discover the bug that would not let me log on. You would think that Amazon would fix such a bug immediately. For some time now someone has been asleep at the wheel at Amazon as far as tech products are concerned. Or maybe now that there is talk of breaking up big tech companies Amazon has decided that it needs to be less competitive for a while? The decline is evident wherever I look--Amazon Music, Alexa, Kindle, etc. It's really too bad. In any case, to my surprise, using Amazon.ca to log on did work for me. I was immediately able to open my books, view my notes and highlights, etc. I am not in Canada and I don't live in Canada, but for some reason this works.
I just spent over 30 min with a supervisor in Amazon's tech support, but Kindle app still will not register and connect to my acct. I told the agent about this thread and she said it's not legit (iow, this is not a legit Amazon site). I tried changing the "sign in using..." to both .ca as well as .com because I'm in the US, and neither worked. I right clicked on the app and ran as administrator. Didn't work. I logged out of Amazon on my browser and relogged in to make double sure that my password was what I thought it was, because the Amazon rep said the error code  points to a password probably. But my login was successful on the Amazon site in the browser. I uninstalled, reinstalled the Kindle app probably at least 6 times. Didn't work. I restarted my computer. Didn't work. I ran into this problem with a new ipad several months ago, and the fix for that was that I had to install the Amazon app and login to the app, then it allowed me to login on the Kindle app. Unfortunately that didn't work on this PC. The Amazon supervisor said they will check into this and call me back in a few days. I will post an update hopefully then. If anyone has the answer since .ca didn't work, could you update this thread please?
I used default when I logged in and i ran a test last night or the night before by completely uninstalling the App from my Windows 10 device, installing a new download from the Amazon site and it logged right in with no problems
I have a windows 8 that I can't get my Kindle for PC to register I even tried to change it from Amazon com to Amazon CA Per suggestions. I have tried everything that Amazon has told me to do. I even went so far as to talked to Kindle. Nothing works. Any other suggestions?