The predefined order of PDF files is not respected when combining these via the API

Hi ​@StevenDerveauxKorian ,

PDF Services combines files in the exact order you pass them to the combine operation – there is no extra sorting on the service side. If the output order is wrong, it’s almost always due to how the assets list is built in your code, not the API itself.

In your screenshot you do:

List<IAsset> assets = pdfServices.UploadAssets(streamAssets);

var builder = CombinePDFParams.CombinePDFParamsBuilder();
for (int i = 0; i < assets.Count; i++)
    builder.AddAsset(assets[i]);

Two key points:

• Don’t assume UploadAssets(streamAssets) returns assets in the same order as streamAssets. The SDK doesn’t promise that; treat that list as unordered.
• To guarantee order, either:
  • Upload and add in the same loop, in your desired sequence:

    var builder = CombinePDFParams.CombinePDFParamsBuilder();
    
    foreach (var streamAsset in orderedStreamAssets) // already in your desired order
    {
        IAsset asset = pdfServices.UploadAsset(streamAsset);
        builder.AddAsset(asset);  // order is now exactly this loop order
    }
    
    var combineParams = builder.Build();
    

  • Or keep your own mapping { originalIndex -> asset } and sort by that before calling AddAsset.
• As long as you call builder.AddAsset in the order you want, the combined PDF will follow that order, same as the standard Combine Files examples in the docs where order is defined by the sequence of added inputs https://experienceleague.adobe.com/en/docs/acrobat-services-learn/tutorials/usecases/employeeonboarding