Hello!
I just got the web interface to update the nextcloudsoftware, when I update to 18.0.11 it shows
InvalidArgumentException: Column name "nc_5047_flow_operations"."entity" is NotNull, but has empty string or null as default.
The nextcloud.log is empty
But I don’t know how to fix it. I’m really sorry, can anybody help me?
I would recommend to use the search function of this forum first next time, because the problem has already been addressed multiple times in the past:
https://help.nextcloud.com/search?q=flow_operations%22.%22entity%22%20is%20NotNull
Yes, but I didn’t found a working solution. I’m sorry, I’m new at NextCloud and can’t find a working solution to fix it. I don’t want to lose my data
The solution can be found be reading through the list postings and following the available solutions, which are marked as “solution” right below the initial posting of a thread.
Why should you loose any data, when you have a working backup in place? 
I did read them, but not any one is working for me. I’m looking since December for an solution, but can’t find anything, that works. is there any way to fix this by reinstalling nextcloud? how can I download my backup? I it possible to deinstall and install NC new on my FTP and reupload my backup?