Error When Updating Order Status

While updating the Order status, the following error may occur.

with LocationPaths (TmStockLocationID, FullPath)
As
(
    Select loc.TmStockLocationID,CAST(loc.Name AS nvarchar(max)) AS FullPath
    From TmStockLocation loc (NOLOCK)
    where loc.ParentID is null
    and loc.RowDeleted = 0
    AND loc.TmUnitID = @0

    UNION ALL

    Select loc.TmStockLocationID, Roots.FullPath + '\' + CAST(loc.Name AS nvarchar(max)) AS FullPath
    From TmStockLocation loc (NOLOCK)
    INNER JOIN LocationPaths AS Roots
            on Roots.TmStockLocationID = loc.ParentID
    and loc.RowDeleted = 0
    AND loc.TmUnitID = @0
)
SELECT '' [ChangedFields], TmStockLocation.TmStockLocationID, TmStockLocation.TmUnitID, TmStockLocation.Name, TmStockLocation.Coord, TmStockLocation.SortBy, TmStockLocation.ParentID, TmStockLocation.MovableAsset, TmStockLocation.OriginalUnitID, TmStockLocation.TransitLocation, TmStockLocation.MovableAssetStatus, TmStockLocation.TmLocationOnUnitID, TmStockLocation.LocationType, TmStockLocation.ExternalID, LocationPaths.FullPath
FROM TmStockLocation (NOLOCK)
LEFT JOIN LocationPaths on LocationPaths.TmStockLocationID = TmStockLocation.TmStockLocationID
WHERE TmStockLocation.RowDeleted = 0
   AND TmStockLocation.TmUnitID = @0
ORDER BY LocationPaths.FullPath

The issue is caused when SQL constructs the "full location" path, which times out due to missing or non-indexed data.

Adding additional indexing to the database will avoid this error occurring.

The needed index can be found attached to this article and needs to be run via SSMS.