Given final block not properly padded. Such issues can arise if a bad key is used during decryption.

This error message typically occurs when decrypting data using block cipher algorithms such as AES, but the decryption process is unable to correctly pad the final block. This can occur for a variety of reasons, including using an incorrect key or IV, or attempting to decrypt data that has been tampered with or corrupted.

One common cause of this error is using a key that is different from the one used to encrypt the data. Double check that you are using the correct key for decryption. Another possible reason is that your data may have been corrupted or modified during transmission. You may want to check that your data has not been tampered with.

If you are using a library or tool to perform the decryption, you may also want to check that you are using the correct algorithm and mode of operation. Some encryption libraries may require specific padding schemes or block sizes, and using the wrong configuration can result in errors.

In general, it is important to ensure that your encryption and decryption processes are properly implemented and tested to avoid issues like this.