I cannot see the answer right now. The /e/ build might be broken, but it is here we would look for the evidence.
I think we need to solve some “correct recovey” issue. What branding is on the “Factory” recovery you used for the manufacturer upgrades ?
If you have the stamina…here’s an earlier e-0.17-p from the time of eOS test builds for pie.
There is also a newer Lineage recovery here that might be worth a shot!
Thanks @Yrdael
There’s only the ones proposed by /e/ team.
I had received an error accessing that page yesterday, so I was uncertain.
Back to the “Format data” issue (known to cause Error 7). It looks like your “Zenfone incremental ROMs” sorted the “Format data” issue there. I understand “Format data” was not required.
Were you sure to Format data when you changed to yesterday’s Unofficial TWRP + /e/ ?.
Oddly that method is not included in our instructions ! Only sideload is recommended.
The fact that the device has only unofficial TWRP might point to something irregular in the hardware.
Hello again,
Thank you @chrisrg for the ideas. I tried this early build but it ended up with the same result. Also, lineage recovery did install properly but I can’t sideload due to an error (can’t mount /cache no such directory and such…) and there’s no option to install via SDcard. So, following this way of thinking I went looking for another recovery, but alas no option available for this model on either of these groups :
https://wiki.orangefox.tech/en/home
And no wonder since they are derivatives of TWRP. I was still hoping they’d have it somehow.
No, I can’t be sure I did that since it was some time ago, but I made this step an automatism for me “always clean up before install”, so I assume I did.
So what you mean is that I shouldn’t have formatted the data in the first place ?
I know, it actually used to be on some devices, like the samsung S4 last year or something. Thing is, this is the only way I have to get to the installation process without any errors. I’m still trying sideload from time to time just because it’s supposed to be working from what’s said in the documentation.
Just to review my advice a bit; way back at Post #28 I said
Wipe of data is also associated with Error 7, so I would definitely do it on change of Android version.
I believe that to be correct. On regular updates wipe cache + ART is sufficient, when Android version change is involved Data should be wiped.
While you were doing incremental manufacturer’s updates, you were following their guidance, so I would expect their guidance to be sufficient. I think I understood you to report that under their guidance this data wipe was not specified. Fine by me so far 
That “tiresome night” I had a concern that you had got into the habit of omitting the data wipe from your workflow.
Then I asked “were you sure you did the data wipe”, the time that you went to /e/ install, following the long run of “manufacturer upgrades”.
I am just spelling that out, as I think that is the point you are asking me to clarify.
I really don’t think you can do any harm (other than lose your data) if you wipe data on any occasion.
I did wipe in between each installation.