300 EFI Boot entries was created in the NVRAM for Ubuntu

[Xavier BRASSOUD]

Dear Support Team,

When I've upgrade Ubuntu from 16.04 to 18.04, a issue cause creation of new boot entries in NVRAM at each (re)boot of my laptop.
I'm able to access to Ubuntu by manually select the right EFI file to launch the OS.

My logical configuration :
 - Triple Boot : OSX, Windows, Ubuntu
 - EFI partition with custom file structure (for example Ubuntu is not located to the default path \EFI\ubuntu\shimx64.efi, but in other path).

This setup work like a charm, however when I've upgraded Ubuntu, I've missed to response "no" to the Grub installer prompt when asking for "set to defaut NVRAM settings"... So Ubuntu break my EFI Boot MGR. That's not the bug here, the bug appear when the laptop restart, I've got a message System BootOrder not found. Initializing defaults."
That's ok, I'm abble to reconfigure my EFI Boot MGR with "efibootmgr" tool for example.
So I've seen the bug when I run this command : efibootmgr -v
At least 300 entries in my EFI Boot MGR was created for Ubuntu ! (you can see the output on file attachement) So my NVRAM was sattured by all of this entries...

My question : Is it possible to create only 1 entry in EFI Boot MGR when the file \EFI\ubuntu\shimx64.efi is'nt found ? And not create a new entry each time the laptop reboot ?
I've solved this by erase this entries one by one with a script...

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.28
ProcVersionSignature: Ubuntu 4.15.0-39.42-generic 4.15.18
Uname: Linux 4.15.0-39-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Fri Nov 23 00:07:12 2018
InstallationDate: Installed on 2017-10-31 (387 days ago)
InstallationMedia: Ubuntu 16.04.3 LTS "Xenial Xerus" - Release amd64 (20170801)
PackageArchitecture: all
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
Symptom: release-upgrade
UpgradeStatus: Upgraded to bionic on 2018-11-19 (3 days ago)
VarLogDistupgradeTermlog:

[Xavier BRASSOUD (xavier73)]

I forgot to mention that the saturation of the NVRAM causes a considerable slowdown of the computer at startup.

I hope the solution I've submitted is possible to do, that will help other users in the future, thank's ! ;)

*sorry for my bad english, I'm guy from "baguette" country