Small correction, not bech 23, correct name is bech32 (address starting with bc1) native SegWit.

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How can I upgrade to Nested Segwit, addresses starting with 3 on Electrum.
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Electrum has never allowed direct creation of nested SegWit addresses - the only way was to have such an address in Electrum is to use Iancoleman's BIP39 seed generator and then enter such a seed into Electrum. For more information, see the following thread.

How to get SegWit addresses starting with a "3" in Electrum?