+1 on the Object error. Fresh install. No previous versions:
2020/08/12 09:45:45 http error: Unable to proxy the request via the Docker socket (err=Object not found inside the database) (code=500)
Running Portainer Addon 1.2.1, Protection Mode is off.
New install of HASS.Io on my Pi3B - comes default w/Portainer 1.2.1, so I guess I’m waiting for a patch too 
Same issue for me too - fresh install and I’m getting the ‘object not found inside the database’ error…
As this error seems not to be fixed by a new version soon, maybe the addon version 1.2.1 should just be revoked so that users are able to install the working version 1.2.0.
Is there a way to install v1.2.0 via ssh or something?
I do not have a snapshot of the old version.
I tried to modify a snapshot to install v1.2.0 instead of 1.2.1 without luck 
Is it possible that someone take a partial snapshot with only Portainer 1.2.0 in it? And load it in to another system? Or is this causing issues?
–EDIT–
I’ve found a solution until the problem is solved.
As soon as a new version is available, this version can be uninstalled and the official version can be reinstalled.
@Rijswijker - I asked the same thing in the HA Discord chat and @Yass15 gave me the goods!!
Locate your addons folders (mine is /usr/share/hassio/addons). Download the previous release of Portainer off Github Portainer addon (https://github.com/hassio-addons/addon-portainer/archive/v1.2.0.zip). Move the folder “portainer” inside the zip file into your addons/local folder. Re-start HA/ clear browser cache and you should see a new “local addon” Portainer on addons. Click install and it’ll install the previous version.
you’ll see it on add-on store section at the very top: https://imgur.com/JII3GXB
LOL - yeah - I think I posted at the same time as you found the solution too! 
may be a foolish question, i want to install Portainer add on in my HA. I am not able to find the Portainer in add on store. Can any one please help me what is wrong?
As alternate i have tried manual add on addition by following Home Assistant Community Add-on: Portainer . I have placed the ‘portainer’ folder to add on>local folder on my HA. Under supervisor I dont see portainer under local add on list. I have reloaded it, i have restarted HA, cleared browser cache , but still can see portianer under local add on list in add on store.
It will only show if you have enabled advanced mode in your profile settings.
Thanks Man1, issue resolved, much appreciated your quick support. 
Will we see an update to the new 2.0 release?
Would also love for an update to this add-on so that it can be usable. Thank you!
how is it not usable?
I didnt realize I had version 1.2.1 and was still getting object not found error. I mistakenly thought it was updated!
I cant pull docker image more than 1 GB image
actually i want to add shinobi docker image
Hi all, is anyone else having any issues trying to open portainer addon. When i went to the addon I just got a blue circle spinning around so I uninstalled the addon through the terminal and now even when I go to the addon from the store i get the same blue circle. Any ideas?
Cheers
Do it on the CLI.
I have HA installed with the supervised image from here. Any idea how to backup custom containers (or lets say better the persistent volumes)?
I’m using the GDrive Backup Addon but it sadly does not include custom container configs.
managed to figure it out on myself. Maybe it’s interesting for someone else, so here it is:
I just had a look at the Containers that come with HA and saw, that they are mounted somewhere at “/mnt/data/supervisor/” so I created Subfolders for every mount point that i need at: “/mnt/data/supervisor/homeassistant/docker_files/” (/mnt/data/supervisor/homeassistant/ is the “config” folder) that folder is persistent and gets included by snapshots. Also I’m able to access them with the SMB Addon.