you need to get rid of these try/catch statements, they are everywhere.

Use one Try Catch Statement

instead of what you have

public static bool ConvertToBase64(string inputFile, string outputFile)
{
    try
    {
        using (FileStream inputFileStream = new FileStream(inputFile, FileMode.Open), 
               outputFileStream = new FileStream(outputFile, FileMode.Create))
        {
            try
            {
                ToBase64Transform base64Transform = new ToBase64Transform();
                //Buffers for read/write operations
                Byte[] outputBuffer = new byte[base64Transform.OutputBlockSize];
                Byte[] inputBuffer = new byte[inputFileStream.Length];
                //Offset to count the number of bytes transformed so far
                int inputOffset = 0;
            
                try
                {
                    inputFileStream.Read(inputBuffer, 0, (int)inputFileStream.Length);
                }
                catch(Exception ex)
                {
                    return false;
                }
                
                if (false == base64Transform.CanTransformMultipleBlocks)
                {
                    while (inputBuffer.Length - inputOffset > base64Transform.InputBlockSize)
                    {
                        //Transform a block of input data
                        base64Transform.TransformBlock(inputBuffer, inputOffset, inputBuffer.Length - inputOffset, outputBuffer, 0);
                        inputOffset += base64Transform.InputBlockSize;
                    
                        try
                        {
                            outputFileStream.Write(outputBuffer, 0, base64Transform.OutputBlockSize);
                        }
                        catch(Exception ex)
                        {
                            return false;
                        }
                            
                        //Insert a new line after 76 characters
                        if (inputOffset % 19 == 0)
                        {
                            byte[] newline = Encoding.ASCII.GetBytes(Environment.NewLine);
                            outputFileStream.Write(newline, 0, newline.Length);
                        }
                    }
                }
            
                //Final block transform
                try
                {
                    byte[] lastBlock = base64Transform.TransformFinalBlock(inputBuffer, inputOffset, inputBuffer.Length - inputOffset);
                    outputFileStream.Write(lastBlock, 0, base64Transform.OutputBlockSize);
                }
                catch(Exception ex)
                {
                    return false;
                }
            
                if (false == base64Transform.CanReuseTransform)
                {
                    base64Transform.Clear();
                }
            }
            catch(Exception ex)
            {
                return false;
            }
        }
    }
    catch(Exception ex)
    {       
        return false;
    }

    return true;
}

Only Catch when you need to catch. Like this

public static bool ConvertToBase64(string inputFile, string outputFile)
{
    try
    {
        using (FileStream inputFileStream = new FileStream(inputFile, FileMode.Open), 
                outputFileStream = new FileStream(outputFile, FileMode.Create))
        {
            ToBase64Transform base64Transform = new ToBase64Transform();
            //Buffers for read/write operations
            Byte[] outputBuffer = new byte[base64Transform.OutputBlockSize];
            Byte[] inputBuffer = new byte[inputFileStream.Length];
            //Offset to count the number of bytes transformed so far
            int inputOffset = 0;
        
                inputFileStream.Read(inputBuffer, 0, (int)inputFileStream.Length);
            
            if (false == base64Transform.CanTransformMultipleBlocks)
            {
                while (inputBuffer.Length - inputOffset > base64Transform.InputBlockSize)
                {
                    //Transform a block of input data
                    base64Transform.TransformBlock(inputBuffer, inputOffset, inputBuffer.Length - inputOffset, outputBuffer, 0);
                    inputOffset += base64Transform.InputBlockSize;
                
                    outputFileStream.Write(outputBuffer, 0, base64Transform.OutputBlockSize);
                    
                        
                    //Insert a new line after 76 characters
                    if (inputOffset % 19 == 0)
                    {
                        byte[] newline = Encoding.ASCII.GetBytes(Environment.NewLine);
                        outputFileStream.Write(newline, 0, newline.Length);
                    }
                }
            }
        
            //Final block transform
            byte[] lastBlock = base64Transform.TransformFinalBlock(inputBuffer, inputOffset, inputBuffer.Length - inputOffset);
            outputFileStream.Write(lastBlock, 0, base64Transform.OutputBlockSize);
            
            if (false == base64Transform.CanReuseTransform)
            {
                base64Transform.Clear();
            }
        }
    }
    catch(Exception ex)
    {       
        return false;
    }
    return true;
}

If there is an exception let it bubble up to where you want to catch it, not where it happens, you aren't even keeping the stack trace, so it doesn't matter where you catch it. so just do one try/catch statement here.