Would really like a built in solution into the library for this coming release. I have an excessive amount of overhead because of this and this issue is quite old. Please see what you can do. Seems like a simple null check would be sufficient.

Wanted to amend my original solution. I found that when I used the solution below in an Asp.Net core solution that it would throw an error where my Console application would not. Not sure what the deal was, but I found that if I avoid the Encoding conversion part, and just stuck to working with the byte array then all was fine. Here is my new solution which involved creating a new Linq extension method to replace any given SEQUENCE of bytes with another sequence, as is needed in this scenario.

 

        // LINQ ReplaceSequence Extension Method
        public static IList<TSource> ReplaceSequence<TSource>(this IList<TSource> items, IList<TSource> replaceItems, IList<TSource> withItems, IEqualityComparer<TSource> comparer = null)
        {
            comparer = comparer ?? EqualityComparer<TSource>.Default;

            if (replaceItems.Count() != withItems.Count()) throw new Exception($"{nameof(replaceItems)} array and {nameof(withItems)} array must be of equal length.");

            for (var i = 0; i < items.Count(); i++)
            {
                var sequenceMatches = true;

                for (var j = 0; j < replaceItems.Count(); j++)
                {
                    var matchItem = replaceItems[j];

                    if (!comparer.Equals(items[i + j], matchItem))
                    {
                        sequenceMatches = false;
                        break;
                    }
                }

                if (!sequenceMatches) continue;

                for (var j = 0; j < withItems.Count(); j++)
                {
                    items[i + j] = withItems[j];
                }
            }

            return items;
        }

        public static void ApplyPDFFix(byte[] bytes)
        {
            var searchStr = "/DecodeParms[null]";
            var replaceStr = string.Join("", searchStr.Select(e => " "));

            var searchStr_Bytes = Encoding.Default.GetBytes(searchStr);
            var replaceStr_Bytes = Encoding.Default.GetBytes(replaceStr);

            bytes.ReplaceSequence(searchStr_Bytes, replaceStr_Bytes);
        }

 

As Tanya pointed out, this solution can come with any various number of side-affects, so use it with caution OR wait for Telerik to provide an official fix. For me, I needed a programmatic solution NOW. At least this way I don't have to meddle with the actual STORED pdf, and can just alter the bytes in memory.

Quick fix to apply before importing:

 

        public byte[] ApplyPDFFix(byte[] bytes)
        {
            var searchStr = "/DecodeParms[null]";
            var replaceStr = string.Join("", searchStr.Select(e => " "));

            var ansiStr = Encoding.Default.GetString(bytes);

            ansiStr = ansiStr.Replace(searchStr, replaceStr);

            return Encoding.Default.GetBytes(ansiStr);
        }

 

Not sure if it's the "best" way, but it works. Turns out about 10% of the PDF files that I work with are afflicted by this bug.