I have been using SC since version 17.xx always 64bit portable on a Windows 10 PC.
All my video projects were successfully created with SC up to 19.08.
I can open and edit all my 80 old *.mlt (2017-2019) in Shotcut including version 19.09
Now i find errors with older mlt-projects in newer SC (since 19.10):
The versions: 19.10., 19.12.16 and 19.12.23 show errors when opening old *.mlt.
SC ask to correct the project or not.
No matter whether I have it repaired or not, no clips can be previewed that have the filter rotate & scale activated.
If I deactivate rotate & scale, the preview works.
The Sharpen filter always shows the values 0.0% + 0.0%, instead of the original 50.0% + 5.0%.
Other filters i did not tested, cause at first i need a workaround with newer SC versions than 19.10.
I would like to use newer SC versions, especially 19.12.23, but then I can no longer use my old 80 *.mlt.
What can I do?
19.10.20 added keyframes to rotate&scale they also had their parameter range adjusted.
The sharpen filter also was changed in some recent versions including the addition of keyframes.
I would suggest using 19.08 if that’s the last version that is error free with those mlt files but making new projects in 19.12, if you’re using portable versions an “archived” and “current” versions of shotcut should be more than manageable.
Since the old portable versions are available still on github and can be used concurrently with the installed version it seems like a great solution to me, especially with how seldom breaking changes are.
I am having trouble reproducing your problem. Since you are in Germany or at least German, I suspect there is a problem with locale/region decimal separator after the change mentioned here under Project Files: https://shotcut.org/blog/new-release-190615/
But I am surprised or uncertain that your problem does not occur until v19.10. I am also a little uncertain because you use period in your example numeric values, for example “50.0% + 5.0%”, instead of a comma.
I think the best thing to do is attach one of the smaller project files that gives you this problem and then the Shotcut log (View > Application Log…) after you open it and cancel the dialog to repair. Save this log with a .txt extension and attach it along with the .mlt project file.