The usual cause of that message is a plugin that has not been updated for configuration form modernization that was performed in Jenkins 2.277.1. Follow the detailed instructions in the earlier post to identify the plugin causing the issue.
“I get an error …” is hard to remote debug. Try to always include these 3 things.
- what did you try? (Code samples, command lines, screenshots, videos, etc)
- what did happen? (Error messages, description, outputs, stuff)
- what did you expect to happen?
Otherwise, it’s hard for us to get into your context and you’ll have to have someone who is exactly knowledgeable come along.
Refer to “How to report an issue” for the type of information that others will need before they can help you.