I installed OSCAT Basic Library v3.3.3.0.
When I upgraded it to v3.31, OSCAT changed internal link to Standard library v3.3.0.10 from v3.5.15.10.
And I can't download this old version of Standard library now. (Download missing libraries failed.)

It is the common problem after Codesys v3.5 upgrade to a new version or upgrade some libraries.
After that some links to different versions of standard libraries appear in the project
and these libraries don't download.

I'd like to understand why this problem happens and how I can handle it?

Can some standard libraries be downloaded directly from Codesys Store and then installed manually?

Can I read in the documentation about how Codesys handle with different versions of system libraries?
(How does dependency resolving mechanism work? And why may it not work?)

Hey akrabato,

I can't answer your actual question (I'm curious as well).

I can help you fix the OSCAT V3.31 Library. This is how I have corrected this problem for myself:

1) Download the library from the OSCAT website.
http://www.oscat.de/images/OSCATBasic/oscat_basic_331_codesys3.library

2)Open the Library with Codesys (I'm using Schneider Electric Machine Expert). It will most likely ask you to upgrade the project. Select Update

3)Open the Library Manager

4)Right click on the standard library and select "Properties". In the Version section, select the radio button for "Newest version always".

5)Save The Project (OSCAT V3.31 library).

6)Import the OSCAT V3.31 library to the project where you actually need to use it.

I have also come across another method of fixing this. Check out this YouTube video:
https://www.youtube.com/watch?v=ySNp9_Cb6e8

Skip to around 9:40 to see how he handles the problem. He just deletes the newer "STANDARD" library and uses the older one that comes in the OSCAT Basic Library (V3.3.0.10).