Once I create all necessary sub-folders, I get a permission denied instead of file not found.
Basically no saving/accessing of files works with non-preinstalled apps. Even taking pictures with Camera ZOOM FX downloaded from the play store cannot save the pictures I took.
Taking a picture with the built-in camera cannot be opened with QuickPic.
That’s of course always granting the apps permissions to files when they ask for it.
I think I found the “download” issue. I had to reimport sdcardfs. Looks like my old version was broken/imcomplete for O. Anyway firefox downloads at least seem ok.
Will upload a new version soon.
Chris
https://www.androidfilehost.com/?fid=5862345805528055999
This should fix:
Manual APK installing behaviour changed in Oreo. You need to give explicit permission to each app so they can launch the installation. Not every app is compatible with Oreo yet, though: in my Nexus 4 I couldn’t figure out how to make Amaze works and use Dir for that same reason.
I can confirm that the download problem is gone with this version 
Thanks a lot!
Edit: and also the proximity calibration tool now starts properly instead of saying it’s incompatible.
At the moment I am aware of two remaining issues:
Hopefully we’ll get those sorted soon.
Chris
Hello Chris! I tested your rom Lineage_FP2-ota-e7a9f79aad.zip with OpenGapps 8.1 pico, and it works, that is awesome Thanks a lot !
However, I have trouble using root: I tapped on the build number to activate developer settings, then I set root to “Applications and ADB”. After that, when I launched three apps needing root (iSu, Titanium backup and Amaze), I had no pop-up asking for root access and those apps say “device not rooted”… How to configure correctly?
Last question: as soon as you release a new zip, could we upgrade it from version to version just flashing the zip (wiping system before?) and keep all our (non-sytem-) apps installed?
Today I flashed the latest ZIP and all installed apps/settings were still there after the update.
It is also possible to disable one SIM slot in the settings menu - which wasn’t possible on LineageOS 14.1, but only on Fairphone OS and Fairphone Open OS.
It is still a bit buggy though, as I cannot enter the PUK for the second SIM card (phone gets locked, PUK dialog does not appear). After disabling the first SIM card, the PUK dialog appears and prompts me to enter the PUK followed by the new SIM PIN, this however has no effect and the SIM remains blocked prompting for the PUK.
I solved it by booting up with only the locked SIM inserted, the phone prompted for PUK followed by the new SIM PIN and unlocked the SIM successfully.
That’s amazing news! Well done.
I’ll wait a little before flashing this. But I can confirm that the problems with the camera flash aren’t new. 14.1 has the same behaviour.
Is shutdown working :)? Shuting down current LOS leads to a reboot…
Seems that it depends…
Alright, so same behaviour and currently unfixed… thanks.
Since the last build, FM-Radio stopped working for me (see logcat output here).
Could this be related to SELinux now being in strict mode? I guess we need another rule to allow this:
type=1400 audit(0.0:43): avc: denied { execute_no_trans } for path="/system/vendor/bin/init.qcom.fm.sh" dev="mmcblk0p13" ino=2154 scontext=u:r:init:s0 tcontext=u:object_r:vendor_file:s0 tclass=file permissive=0
Good catch! Will try to fix.
Chris
So, I will try an installation tonight. If I backup my apps per Titanium Backup, can I reinstall them in Oreo 
or do I have to install them new?
So, installation didn’t work. Will try again tomorrow. Wiped everything (cache, internal storage, sytstem and data), then flashed zip. Never came out of booting.
Sounds like my first try with encryption still in place.
If you have encrypted your phone before installing LineageOS 15.1, you will have to remove the encryption with Wipe - Format Data in TWRP first.
No encryption on my side. Can i I install the last Ota zip or should I start at the top and ‘add on’?
These are full OS builds, no incremental updates, same as with LineageOS 14.1.
Alternatively, you could use the LineageOS 15.1 recovery given in the first post to wipe everything and install the ZIP via ADB sideload (it didn’t like my SD card at least), and see whether that changes anything.