Thank you alex. I did indeed research and I already know the meaning of error 7. I thought maybe someone can confirm above mentioned files are working or maybe an older twrp version is working. I already tried different files from lineageos.
Updater script does look like this:
assert(getprop("ro.product.device") == "FP2" || getprop("ro.build.product") == "FP2" || abort("E3004: This package is for device: FP2; this device is " + getprop("ro.product.device") + "."););
ui_print("Target: Fairphone/FP2/FP2:6.0.1/FP2-gms-18.04.1/FP2-gms-18.04.1:user/release-keys");
package_extract_dir("install", "/tmp/install");
set_metadata_recursive("/tmp/install", "uid", 0, "gid", 0, "dmode", 0755, "fmode", 0644);
set_metadata_recursive("/tmp/install/bin", "uid", 0, "gid", 0, "dmode", 0755, "fmode", 0755);
run_program("/tmp/install/bin/backuptool.sh", "backup", "/dev/block/platform/msm_sdcc.1/by-name/system", "ext4");
ui_print("Patching system image unconditionally...");
show_progress(0.900000, 0);
block_image_update("/dev/block/platform/msm_sdcc.1/by-name/system", package_extract_file("system.transfer.list"), "system.new.dat.br", "system.patch.dat") ||
abort("E1001: Failed to update system image.");
show_progress(0.020000, 10);
run_program("/tmp/install/bin/backuptool.sh", "restore", "/dev/block/platform/msm_sdcc.1/by-name/system", "ext4");
package_extract_file("boot.img", "/dev/block/platform/msm_sdcc.1/by-name/boot");
show_progress(0.100000, 10);
set_progress(1.000000);
I am not sure how to edit the file. Is it enough to comment out assert line?