Unfortunately we cannot confirm your upgrade request at the moment as the higher class of travel is not available.(119405)

I got the message "Unfortunately we cannot confirm your upgrade request at the moment as the higher class of travel is not available.(119405)" when I was trying to upgrade my tickets (Economy Class S) on Lufthansa site. I checked the Lufthansa site and found that Business Class tickets are still available for sale for my flights.

I wrote an email to support and got the following response in couple of days:

Dear Mr. Q,

Thank you for your e-mail.

We are pleased that you would like to redeem your miles for an upgrade and regret all the more that you received an incorrect error message. Should you still not succeed to request the upgrade at www.miles-and-more.com < Spend Miles > Flights > Upgrade Awards > Book Upgrade Award <, just call your local Miles & More Service Team. You will find the number on our homepage under < Help & Contact > Contact by Phone <. For this call you will need to have your customer or card number and 5-digit PIN to hand. However, kindly bear in mind we cannot check the availability of award seats for upgrades in advance. You might also be interested to know that you can ask at check-in if an ad-hoc upgrade against miles can be issued should the Business Class not get confirmed a day before departure. 

It would give us great pleasure to issue the desired award for you in the near future.

Sincerely,
Your Miles & More Service Team

I tried couple of more times to upgrade via site and was facing the same "incorrect error message". I decided to call.

Summary of the phone call:

• It is better to call Miles & More Service Team and ask for an upgrade
• The support person will ask your card number, first three digits of the PIN and booking or ticket number and will put your request into waiting list
• There is no way to check how much persons are in the waiting list and in turn, there is no way to check the probability that your request will be served and upgrade will be awarded
• Availability of higher class tickets for sale does not guarantee that upgrade will be awarded. "The System" somehow determines whether upgrade can be awarded
• There is no notification that upgrade is awarded. You have to check your booking online (class should change) or call Miles & More Service Team
• Upgrade will not change amount of miles that you will get (i.e., if you had economy and upgrade to business, you will get the same amount of miles if you will travel economy)
• If you will decide to change/cancel your upgraded tickets, spent miles will be returned to your account