A failed ETH/ERC20 transaction can be viewed on blockchain explorer (see: Why was my transaction rejected?).


Out of Gas example:



This means that your ETH/ERC20 transaction ran out of assigned Gas Limit when executing Smart contract operation on the Ethereum Virtual Machine (EVM) (Usually "Send" for the user). This most commonly happens with ERC20 tokens as they consume much more gas than plain ETH.


In such cases use higher GAS LIMIT to allow more gas to be spend. The default limit for ERC20 token transactions in the BC Vault application is set to 150000, set it to 200000 or even higher if you encounter "Out of gas".


There is no way to predict the actual gas usage as it fluctuates wildly and is token/smart contract function dependant!


Note: This is just the "upper cap" you allow to be used (highest possible cost) to protect you against erroneous functions that could result in huge costs. The spent gas will not be returned to you if transaction fails with "Out of gas"! This is nature of ETH blockchain and has nothing to do with crypto wallets at all (see: What are Fees?).


See also: What is Gas Price and Gas Limit (ETH, ERC20)?