5stepsapart

@cocreation, I also experience this error on ALL 7 separate sites I am managing since updated to 3.4.0

It seems the archives did back up to Dropbox, the zip file is more or less the same size as those created without this error before.

Here are the codes from one of the sites (I swapped the identity into *my name*), the error codes from other sites are more or less identical:

[03-Jun-2017 03:09:03] Backup archive created.
[03-Jun-2017 03:09:03] Archive size is 56.79 MB.
[03-Jun-2017 03:09:03] 257 Files with 83.69 MB in Archive.
[03-Jun-2017 03:09:03] 1. Try to send backup file to Dropbox …
[03-Jun-2017 03:09:05] Authenticated with Dropbox of user: *my name*
[03-Jun-2017 03:09:05] Uploading to Dropbox …
[03-Jun-2017 03:09:05] Beginning new file upload session
[03-Jun-2017 03:09:05] Uploading 4 MB of data
[03-Jun-2017 03:09:09] Uploading 4 MB of data
[03-Jun-2017 03:09:11] Uploading 4 MB of data
[03-Jun-2017 03:09:13] Uploading 4 MB of data
[03-Jun-2017 03:09:15] Uploading 4 MB of data
[03-Jun-2017 03:09:17] Uploading 4 MB of data
[03-Jun-2017 03:09:19] Uploading 4 MB of data
[03-Jun-2017 03:09:20] Uploading 4 MB of data
[03-Jun-2017 03:09:23] Uploading 4 MB of data
[03-Jun-2017 03:09:25] Uploading 4 MB of data
[03-Jun-2017 03:09:27] Uploading 4 MB of data
[03-Jun-2017 03:09:28] Uploading 4 MB of data
[03-Jun-2017 03:09:32] Uploading 4 MB of data
[03-Jun-2017 03:09:33] Uploading 4 MB of data
[03-Jun-2017 03:09:35] Uploading 810 KB of data
[03-Jun-2017 03:09:37] Finishing upload session with a total of 57 MB uploaded
[03-Jun-2017 03:09:40] Backup transferred to /backwpup_4e881c03_2017.06.03-03h06.zip
[03-Jun-2017 03:09:40] ERROR: Call to undefined method BackWPup_Destination_Dropbox_API_Request_Exception::error()
[03-Jun-2017 03:09:43] 2. Try to send backup file to Dropbox …
[03-Jun-2017 03:09:44] Authenticated with Dropbox of user: *my name*
[03-Jun-2017 03:09:44] Uploading to Dropbox …
[03-Jun-2017 03:09:44] ERROR: Call to undefined method BackWPup_Destination_Dropbox_API_Request_Exception::error()
[03-Jun-2017 03:09:46] 3. Try to send backup file to Dropbox …
[03-Jun-2017 03:09:47] Authenticated with Dropbox of user: *my name*
[03-Jun-2017 03:09:47] Uploading to Dropbox …
[03-Jun-2017 03:09:47] ERROR: Call to undefined method BackWPup_Destination_Dropbox_API_Request_Exception::error()
[03-Jun-2017 03:09:49] 4. Try to send backup file to Dropbox …
[03-Jun-2017 03:09:50] Authenticated with Dropbox of user: *my name*
[03-Jun-2017 03:09:50] Uploading to Dropbox …
[03-Jun-2017 03:09:50] ERROR: Call to undefined method BackWPup_Destination_Dropbox_API_Request_Exception::error()
[03-Jun-2017 03:09:52] 5. Try to send backup file to Dropbox …
[03-Jun-2017 03:09:53] Authenticated with Dropbox of user: *my name*
[03-Jun-2017 03:09:53] Uploading to Dropbox …
[03-Jun-2017 03:09:53] ERROR: Call to undefined method BackWPup_Destination_Dropbox_API_Request_Exception::error()
[03-Jun-2017 03:09:55] 6. Try to send backup file to Dropbox …
[03-Jun-2017 03:09:55] Authenticated with Dropbox of user: *my name*
[03-Jun-2017 03:09:55] Uploading to Dropbox …
[03-Jun-2017 03:09:56] ERROR: Call to undefined method BackWPup_Destination_Dropbox_API_Request_Exception::error()
[03-Jun-2017 03:09:58] 7. Try to send backup file to Dropbox …
[03-Jun-2017 03:09:59] Authenticated with Dropbox of user: *my name*
[03-Jun-2017 03:09:59] Uploading to Dropbox …
[03-Jun-2017 03:09:59] ERROR: Call to undefined method BackWPup_Destination_Dropbox_API_Request_Exception::error()
[03-Jun-2017 03:10:01] 8. Try to send backup file to Dropbox …
[03-Jun-2017 03:10:02] Authenticated with Dropbox of user: *my name*
[03-Jun-2017 03:10:02] Uploading to Dropbox …
[03-Jun-2017 03:10:03] ERROR: Call to undefined method BackWPup_Destination_Dropbox_API_Request_Exception::error()
[03-Jun-2017 03:10:05] 9. Try to send backup file to Dropbox …
[03-Jun-2017 03:10:05] Authenticated with Dropbox of user: *my name*
[03-Jun-2017 03:10:05] Uploading to Dropbox …
[03-Jun-2017 03:10:06] ERROR: Call to undefined method BackWPup_Destination_Dropbox_API_Request_Exception::error()
[03-Jun-2017 03:10:07] 10. Try to send backup file to Dropbox …
[03-Jun-2017 03:10:07] Authenticated with Dropbox of user: *my name*
[03-Jun-2017 03:10:08] Uploading to Dropbox …
[03-Jun-2017 03:10:08] ERROR: Call to undefined method BackWPup_Destination_Dropbox_API_Request_Exception::error()
[03-Jun-2017 03:10:10] ERROR: Step aborted: too many attempts!
[03-Jun-2017 03:10:10] 1. Trying to check database …
[03-Jun-2017 03:10:11] Database check done!
[03-Jun-2017 03:10:11] One old log deleted
[03-Jun-2017 03:10:11] ERROR: Job has ended with errors in 226 seconds. You must resolve the errors for correct execution.