Google Drive is saying "Sorry, Backup and Sync needs to quit."?
UPDATE: March 16, 2017 4:22:00 PM PDT
This will be the last update I post here from the RSS feed unless some other significant information is posted.
The problem with Google Drive should be resolved. We apologize for the inconvenience and thank you for your patience and continued support.
The Windows client will automatically update with this fixed version within the next 10 hours. Alternatively, affected users can download the updated version of the client from https://www.google.com/drive/download/. Affected Windows 10 users may be required to sign in to their Google account within the client.
UPDATE from Google March 16, 2017 2:58:00 PM PDT:
Includes official repair information
Google Drive service has already been restored for some users, and we expect a resolution for all users within the next 12 hours. Please note this time frame is an estimate and may change.
We are deploying an updated client now. The Windows client will automatically update with this fixed version within the next 12 hours. Alternatively, affected users can download the updated version of the client from https://www.google.com/drive/download/. Affected Windows 10 users may be required to sign in to their Google account within the client.
This is the latest update. There are more updates at the RSS link below.
This appears to be a rather widespread issue: https://www.reddit.com/r/google/comments/5zrwwp/google_drive_is_now_backup_and_sync_error/
Google may have released an internal build of a new version of Google Drive/Backup and Sync by mistake.
We can assume they're aware of this and are working to resolve the issue. In the meantime, if the uninstall/reinstall suggestions of other answers do not resolve the issue, just wait a bit.
Google themselves have also released a notice: https://www.google.com/appsstatus#hl=en&v=issue&sid=4&iid=d9bab8e4a0fdfb97d4ac42a2c918af14
3/16/17, 11:41 AM We're aware of a problem with Google Drive affecting a significant subset of users. The affected users are able to access Google Drive, but are seeing error messages and/or other unexpected behavior. We will provide an update by 3/16/17, 12:41 PM detailing when we expect to resolve the problem. Please note that this resolution time is an estimate and may change. Some users of the Google Drive Sync client will be receiving the error message "Sorry, Backup and Sync needs to quit."
We have identified the root cause of the issue and are implementing a potential fix now.
If you wish to receive notice of the resolution quickly
Here's an RSS feed for the Google Drive application status: https://www.google.com/appsstatus/rss/en
The Google Product Forums will be updated as the issue progresses as well:
https://productforums.google.com/forum/#!topic/drive/Km-e-xRJ9b4;context-place=forum/drive
The issue is caused by Google.
They released a Status message under the Google Drive Status Dashboard:
We're aware of a problem with Google Drive affecting a significant subset of users. The affected users are able to access Google Drive, but are seeing error messages and/or other unexpected behavior. We will provide an update by 3/16/17, 8:41 PM detailing when we expect to resolve the problem. Please note that this resolution time is an estimate and may change. Some users of the Google Drive Sync client will be receiving the error message "Sorry, Backup and Sync needs to quit."
We have identified the root cause of the issue and are implementing a potential fix now.
Update on the Issue:
Our team is continuing to investigate this issue. We will provide an update by 3/16/17, 9:29 PM with more information about this problem. Thank you for your patience. Some users of the Google Drive Sync client for Windows will receive the error message "Sorry, Backup and Sync needs to quit" and will be unable to use the client. Other Sync clients are not affected. Affected users may continue using the Google Drive web interface and mobile applications.
We have identified the root cause of the issue and are implementing a potential fix now.