When the error 7 occurs, there are a few solutions:
- Downgrade from TWRP 3.4.0 to TWRP 3.3.1 (but you aren’t on this version).
- Update from an old version of TWRP to TWRP 3.3.1 (by downloading the new .img file, going into TWRP > Install > selecting img instead of zip files > selecting the new .img file to install it).
- Your device is not compatible with the zip file you want to install.
- Look at this topic.