Simpler solution would be Export all private keys from old Electrum version and import it to new Electrum version.
Just make sure the computer/notebook is secure and clean from malware/spyware.
Not just the system needs to be free from malware/spyware while importing keys into new Electrum wallet, the wallet itself needs to be downloaded from the main source here:
And you must be aware of this fact mentioned there:
"Warning: Electrum versions older than 3.3 can no longer connect to public servers, and must be upgraded. This is in order to prevent user exposure to phishing messages. Do not download Electrum from any another source than electrum.org."