TWRP: vendor partition is not existed

I try to flash LineageOS on a OnePlus 5 (cheeseburger). I installed TWRP 3.3.0-0 from [here](https://sourceforge.net/projects/cheeseburgerdumplings/files/16.0/cheeseburger/recovery/twrp-3.3.0-0-20190427-codeworkx-cheeseburger.img/download) . I repeatedly wiped the partitions. What I cannot manage is to adb sideload LineageOS [16.0](https://mirrorbits.lineageos.org/full/cheeseburger/20190509/lineage-16.0-20190509-nightly-cheeseburger-signed.zip) . I get this message: Starting ADB sideload feature... Installing zip file '/sideload/package.zip' Error: Vendor partition doesn't exist! Updater process ended with ERROR: 7 I have read [here](https://www.reddit.com/r/LineageOS/comments/9vu4lj/oneplus_5t_failure_to_install_los_151/) that I should install the latest stock ROM (from [here](https://www.oneplus.com/support/softwareupgrade/details?code=5)) , but that results in almost the same error message: Starting ADB sideload feature... Installing zip file '/sideload/package.zip' vendor partition is not existed, exit ota!! Updater process ended with ERROR: 7 How can I create/populate/fix that vendor partition?