There is a bug in the latest version 7.9 LTS build 26994:
Steps to reproduce: Click on https://sonarqube.domain/quality_gates/show/2
2019.07.06 20:16:29 ERROR web[AWvC2JxiDb32Hg05AKCQ][o.s.s.w.WebServiceEngine] Fail to process request http://sonarqube-test.local/api/qualitygates/search?gateId=2&page=1&pageSize=100&selected=selected
org.apache.ibatis.exceptions.PersistenceException:
Error querying database. Cause: com.microsoft.sqlserver.jdbc.SQLServerException: Incorrect syntax near the keyword ‘key’.
The error may exist in org.sonar.db.qualitygate.ProjectQgateAssociationMapper
The error may involve org.sonar.db.qualitygate.ProjectQgateAssociationMapper.selectProjects-Inline
The error occurred while setting parameters
SQL: SELECT proj.id as id, proj.kee as key, proj.name as name, prop.text_value as gateId FROM projects proj LEFT JOIN properties prop ON prop.resource_id=proj.id AND prop.prop_key=‘sonar.qualitygate’ AND prop.text_value = ? where proj.qualifier = ‘TRK’ and proj.enabled = 1 and proj.main_branch_project_uuid is null and proj.copy_component_uuid is null and proj.organization_uuid=? and prop.text_value IS NOT NULL order by proj.name
Cause: com.microsoft.sqlserver.jdbc.SQLServerException: Incorrect syntax near the keyword ‘key’.
Log: https://gist.github.com/jakobjs/5bea79dd24591bf6a670ce6859563d6d
Screenshot:

I have only seen the slow migrate warning for this version.