Upgrade process - hate it

We are currently 4 major versions delayed for our SDP and the upgrade process is really getting uncomfortable. Imagine, we are required to go through all versions to reach the latest version. It is like going through:

Windows XP -> Windows Vista -> Windows 7 -> WIndows 8 -> Windows 10
Android 4.3 -> Android 4.4 -> Android 5.0 -> Android 6.0 -> Android 7.0

It would have been OK if the upgrade was smooth and flawless but it was not.

Pain Points:

Long backup hours for DB and FileAttachments - 6+ hrs of the required DB backup and File Attachments then failed due to an error at the end.
Errors after Errors - 1 error identified and fixed, then another error showed up -- SDP support identified and fixed.
Custom Jar after Custom Jar - imagine every time an error shows up, a custom .jar is provided -- why not apply the fix in one way or another on the upgrade package?

It is my first time to upgrade SDP and it is not a good experience.

Has anyone experienced the same?