Binance has deactivated their old BNB chain (now called "Beacon Chain") that is implemented in Coinomi. Holders of tokens and assets on that old chain had until November 19th to swap their assets from the old to the new BNB chain, according to their schedule here https://www.bnbchain.org/en/bnb-chain-fusion
Now that the deadline has passed, the process will take longer and be more complex, but Binance made sure that it will still be possible. On the page above you can click the button "how to recover" for their official instructions. The process can be completed with the Trust or Binance extension wallets.
Since Beacon Chain transactions will no longer confirm or count towards the swap process, it is necessary to restore your wallet into one of the suggested apps. If your Coinomi's Recovery Phrase is 12 or 24 words long, you can restore the Phrase directly into their supported wallets to complete the instructions. If your Recovery Phrase has any other number of words, extra steps are needed in order to import your wallet into those apps.
Importing a BNB wallet with 15 or 18 words into the BNB Wallet extension
If your Recovery Phrase has a number of words different from 12 or 24 words, follow the step by step instructions below:
- Open the private key generation tool here https://iancoleman.io/bip39/
- Save the page as an html file and open it on an airgapped device, or turn your device completely offline
- Enter your Recovery Phrase on the text box "BIP39 Mnemonic"
- On the "Coin" selector choose "Ethereum"
- Scroll down to the "Derivation Path" section and select the "BIP32" tab
- Set the "BIP32 Derivation Path" to
m/44'/714'/0'/0
- Scroll down to the "Derived Addresses" list. The private key to your address will be on the last column of the very first row
- Transfer the private key to the device where you will make the swap operation, or into a secure temporary holding area. You can optionally also transfer its associated Ethereum address in order to check that the procedure is being followed correctly.
- Close the key generation tool and clear your device's clipboard. Now it's safe to turn internet back on.
- Open the BNB Chain Wallet extension. Create a new wallet there if you don't have one already
- Click on your Account's "avatar" (usually the letter "A") at the top right corner of the extension window
- Select "Import account"
- Make sure the "Private Key" type is selected and enter the Private Key from the key generation tool
- Click on "Import" to confirm
- Switch to the newly imported account. Its address should be the same as the address shown on the key generation tool
- At the top of the Binance Wallet extension, switch from "BNB Smart Chain network" to "BNB Beacon Chain network"
- You should see that its address is now the same as your BNB wallet's in Coinomi. Now you can proceed with Binance's official instructions.