Until just recently, a desperate solution for messed up url aliases related issues was to truncate ezurlalias_ml table and regenerate nice urls using the existing script.
Currently updateniceurls.php fails with an exception if the table is empty

steps to reproduce:

• truncate ezurlalias_ml table
• execute the legacy script (through SF console)
  => expected result: the script would execute and regenerate all urls
  => actual result. The script will fail with the following error:

    [eZ\Publish\Core\Base\Exceptions\NotFoundException]  
    Could not find 'URLAlias' with identifier '2'