Why am I getting "Error: UTxO Balance Insufficient (2)"?

This error typically means that you don't have enough balance in your wallet to perform the actions you have pending. In the case of a CDP creation, it would most likely mean that you don't have enough collateral tokens in your wallet to lock up in the CDP you're trying to create (e.g., specifying that you want to create a CDP with 300 BTN as collateral but only having 200 BTN in your wallet). In the case of repaying/liquidating a CDP, it most likely means you don't have a large enough synthetic balance to burn in order to repay the CDPs debt. You can check your synthetic balance by hovering over the wallet widget in the top-right corner of the app.

It's also important to note that CDPs accrue interest (see Fees). You can see the accrued amount in the Interest column for each CDP in the Portfolio page. Interest starts accruing immediately, and even a tiny amount can mean that you don't have enough of the synthetic in your wallet to close the CDP.