Does anyone know what does - Fail with error 'ERR_LIMIT_OUT' mean? Thank you!
To know why an error like that is triggered, you have to check the Code of the contract. On etherscan, click on the contract address, and then on the Contract tab (here).
Then, ctrl+f the error name. Here we see that this error is triggered by
require(totalAmountOut >= minTotalAmountOut, "ERR_LIMIT_OUT");
A quick read of the code tells me that this error is triggered when the actual amount of token out of the swap was less than the minimum amount that was specified by the user for the transaction to succeed.
This generally happen when there was a price change between the time the user sent the transaction and the time it was mined.