If you are having issues with getting the QR barcode as I was for re-installing LastPass on my iPhone this is what I discovered. I have had LastPass installed on my desktop for several years. I had LastPass Authenticator installed and active in the Multifactor Options. So I think what happened is when I accidentally deleted LastPass on my iPhone and re-installed it, the active LastPass Authenticator lost its pairing to my iPhone. So I disabled the LastPass Authenticator and re-enabled it and then I proceeded to follow the prompts, got the QR code, answered remaining questions and my iPhone was once again paired to LastPass. Hope this helps anyone else out there pulling their hair out trying to get the QR code. The QR code appeared on my desktop and I scanned it with my iPhone and that was all it took. I really had no idea this process would work but I just took a chance it might and it did. Hopefully LastPass will pass this along as part of the process.