Today I had time to further investigate...

@Jeff Zola: Yes, we checked the release notes. But nothing could explain what was the problem triggered. The option to add Encrypt=False to the connection string is not valid for Oracle databases.

@Jalpal Panchal: The parameterless constructor is not the problem, I've tried it but no success.

I've made updates for the Devart and EF packages:

• From EF 5 to EF 6: no problem
• From EF 6 to EF 7: no problem
• From EF 7 to EF 8: no problem
• From EF 8 to EF 9: Houston we've got a problem....

At this moment it's not clear to me if this is a problem of EF, Devart or if it is because of not updating to .Net 9.

But thanks anyway for your suggestions!