Preliminaries:

• Shopkeepers version: 2.17.1
• Spigot version: This server is running Paper version git-Paper-193 (MC: 1.20.1) (Implementing API version 1.20.1-R0.1-SNAPSHOT) (Git: 581b683) You are running the latest version Previous version: git-Paper-183 (MC: 1.20.1)

• I have checked that my issue/question does not get answered by:
  • The documentation.
  • The FAQ.
  • The Known Issues.
• I have checked all open and closed issues, but none seems to fit my issue/question.

Reproduction on a fresh and up-to-date Spigot server:

I was <able / not able> to reproduce my issue on a freshly set up and up-to-date Spigot server (currently <Insert output of /version command on up-to-date Spigot server>) with the latest version of Shopkeepers (currently <Insert latest tested Shopkeepers version>), with no other plugins and with no kinds of other server or client mods.

The issue:

Provide a detailed description of your problem and add as much information as possible which could help to reproduce the issue.

Include:

• Description of the issue.
• Step-by-step instructions on how to reproduce the issue.
• Observed behavior.
• Expected behavior.
• If items with special attributes are involved: Include instructions on how to create those items.
• Server logs (from server startup until issue). Consider enabling debug mode in the config for additional console output.
• If modified from default: Plugin configurations.
• ... Anything else that might be useful to reproduce and identify the issue.

I joined my server and I noticed that all my shopkeepers were dissapered, and when I wanted to create a new shopkeepers they don't save their products. I viewed logs and saw that all of my shopkeepers weren't loaded with error: "Failed to load shopkeeper 'X': Shopkeeper data migration failed!"
Logs: https://mclo.gs/HbJSfBH
I didn't change the config except debuging(I enabled it after finding this bug)

same issue

Duplicate of #842