Could this be the same as the issue reported here? All dashboards lost after upgrade from 3.1.x to 3.2.1
There’s a migration bug which occurs when fields contain dashes or @-signs. A longer stacktrace would be helpful to verify.
The above-mentioned issue should be fixed in 3.2.2. See this PR for reference: https://github.com/Graylog2/graylog2-server/pull/7448