As Saurik's comment on Reddit today, he is going to release new versions of Cydia and Substrate soon, both of which more than likely will completely break on Electra. If you want to try Electra jailbreak, don't update Cydia version.
However if you updated your Cyida, you could follow our guide as below:
1. Download the .deb file
2. Use the wincp to view your iPhone, put the downloaded file to your device root directory
File protocol- Choose SCP
Host Name – Your Wifi IP Address
Port – 22
User Name – root
Password – alpine
3. Input command "dpkg -i apt7-lib_0.7.25.3-15_iphoneos-arm.deb" and click execute it
4. Wait a moment
5. Run Cydia and repair it