The following steps end up in an error page:
1. Open admin/config/development/import
2. Choose a file that is not a *.tar file.
3. Hit upload.
The following error is thrown:
Exception: Invalid checksum for file "somefile.txt" : 24385 calculated, 262720 expected in Drupal\Component\Archiver\ArchiveTar->_error() (line 637 of /home/juampy/projects/drupal8/core/lib/Drupal/Component/Archiver/ArchiveTar.php).
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