Cannot Delete Some Multiparts (code 3021)


A backup plan terminates with the following error: Cannot delete some multiparts. Some multiparts were not deleted on backup storage for some reason

Error code: 3021


The occurrence of this info message means that automatic multipart deletion failed to delete some unfinished multipart uploads for some reason.

If this info message appears on a constant basis, this may lead to increased storage bills.


Since the reason is unknown, the issue may be on the cloud storage side and can disappear itself on the next backup plan run. The automatic unfinished multipart uploads deletion mechanism works as follows:

Unfinished files (multipart uploads) with a creation date more than 30 days ago are subject to purge.

Purging frequency: once a week

How It Works

Every backup plan at the end starts the unfinished multipart purging mechanism.

The algorithm of the automatic purge consists of two stages:

  1. Search for unfinished multipart uploads is executed.
  2. Unfinished multipart uploads are found and purged.

Purging Necessity Check

The connection must be in regular mode and support automatic deletion of unfinished multipart uploads

  1. All backup plans are checked if a connection supports automatic multipart deletion.
  2. For each plan found, the information on the last 10 runs is analyzed.
  3. The purging mechanism searches for backup plan runs with the 'Success' result with the start date was later than Monday of the current week.
  4. If such a plan is found, then it is assumed that the automatic purging of unfinished files was already carried out during the current week and is not required to be executed again.
  5. In addition to successfully completed plans, running plans on a moment of a check are also checked.

Search for Unfinished Multipart Uploads

The search is performed using a connection in the specified bucket and prefix.

Identification and Purging

Unfinished multipart upload identification occurs while iterating through the received list of unfinished multipart uploads that were found. Unfinished files created more than 30 days ago from the current date are considered to purge.

Such files are deleted immediately.

Delete Unfinished Multipart Uploads Using Storage Provider Console

If the info message still persists, you can try to delete unfinished multiparts straight in your storage provider management console.