The Issue
Within one of our Azure DevOps builds we today started to see the following error when running the SonarQube analysis step:
##[error][SQ] Task failed with status FAILED, Error message: Unrecoverable indexing failures: 1 errors among 1 requests. Check Elasticsearch logs for further details.
Nothing obvious pointed to why this should have started to occur, the SonarQube logs showed nothing more than a longer version of the same message.
The Solution
The solution, as it has been previously, was to clear the SonarQube index.
This can be done by deleting the ES8 folder from the data folder of the SonarQube installation. In my case this was withi an Azure storage account.