I received the following email message from Stack (translated).
Discontinuation of free STACK accounts
In September and October we were startled by two incidents with STACK. Due to the simultaneous failure of several hard drives, part of the data of some free STACK accounts has been affected. The free STACKs are not backed up, which has resulted in files being lost. We regret that very much.
The STACK infrastructure is set up in such a way that a broken hard disk is automatically taken over by a spare disk. Data is distributed in such a way that it is restored in the event of a defect. Since the start of STACK, this has never led to problems, until last September. STACKs are affected by the failure of several hard drives on one storage server at the same time. A smaller, but similar incident subsequently occurred in October.
This shows that we can no longer guarantee the data integrity of free STACK, which is not in line with the quality requirements that we set for our products. That is why we had to make the difficult choice to stop using the free 1TB STACK accounts in the short term.
What does this mean for you?
All free STACK accounts will be discontinued within three months. During this period, we are happy to give you several options to safely store your data. These are:
Upgrade your free STACK to a paid STACK. A backup of your entire STACK is made daily. You will immediately receive a 50% discount for the first 12 months.
Upgrade my STACK
Cancel your free STACK account. Your data will then be immediately deleted by us.
Cancel my STACK
If you do want to keep your data, you can start downloading now. Your data will be deleted by us on 10 February.
Read the article
STACKs that have not been used for more than a year will be locked on November 12. If you log in to the control panel within 14 days, you still have three months (until February 9) to download the data from your free STACK or to switch to a paid STACK. If you fail to do this, your data will be permanently deleted on November 24.
We are sorry that we had to make this choice. Free STACK has brought us and many users a lot of fun. In this article we will tell you more about the history of STACK and how we came to this decision.
Do you have any questions about this email? Here you will find more details, we provide a daily status update and the answers to the most frequently asked questions. Can’t find the answer you’re looking for there? Then our support department is also available Monday to Friday from 09:00 to 24:00 for your questions.
TL;DR - 1TB free plan will be discontinued on February 9 2021. All data will be deleted. Backup your data fast, if you still have it there.