I migrated to a new phone yesterday (Nexus 5 -> Pixel 2) and wanted to restore my WhatsApp chat history on the new device. I've always used the Google Drive backup feature, so I thought this should have been relatively easy. However, during the restoring process, the progress bar gets stuck at 31%. Some minutes later, the app informs me that restoring the messages failed.
What can I do? The Google Drive backup file seems to be corrupted, so I also made a manual copy of the msgstore.db.crypt12 file, so that I could maybe use that in order to restore my history. However, the steps listed on the Whatsapp website (https://faq.whatsapp.com/en/android/20887921/) do not work for me, since it always tries to restore the backup found on Google Drive.