diff --git a/build-tools/prep/ReplaceFileContents.cs b/build-tools/prep/ReplaceFileContents.cs
index 82e5717f..192b84bc 100644
--- a/build-tools/prep/ReplaceFileContents.cs
+++ b/build-tools/prep/ReplaceFileContents.cs
@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -32,41 +32,105 @@ public override bool Execute ()
 				}
 			}
 
-			if (File.Exists (DestinationFile.ItemSpec))
-				File.Delete (DestinationFile.ItemSpec);
+			try
+			{
+				// Validate source file exists
+				if (!File.Exists (SourceFile.ItemSpec))
+				{
+					Log.LogError ($"Source file not found: {SourceFile.ItemSpec}");
+					return false;
+				}
 
-			string[] replacements;
-			if (!String.IsNullOrEmpty (ReplacementFilePath))
-				replacements = File.ReadAllLines (ReplacementFilePath);
-			else
-				replacements = Replacements;
-			var r   = GetReplacementInfo (replacements);
-			using (var i    = File.OpenText (SourceFile.ItemSpec))
-			using (var o    = File.CreateText (DestinationFile.ItemSpec)) {
-				string line;
-				while ((line = i.ReadLine ()) != null) {
-					foreach (var e in r) {
-						line = line.Replace (e.Key, e.Value);
+				// Delete destination if it exists
+				if (File.Exists (DestinationFile.ItemSpec))
+				{
+					try
+					{
+						File.Delete (DestinationFile.ItemSpec);
+					}
+					catch (Exception ex)
+					{
+						Log.LogError ($"Failed to delete destination file '{DestinationFile.ItemSpec}': {ex.Message}");
+						return false;
+					}
+				}
+
+				// Get replacement pairs
+				string[] replacements;
+				if (!String.IsNullOrEmpty (ReplacementFilePath))
+				{
+					if (!File.Exists (ReplacementFilePath))
+					{
+						Log.LogError ($"Replacement file not found: {ReplacementFilePath}");
+						return false;
+					}
+					replacements = File.ReadAllLines (ReplacementFilePath);
+				}
+				else
+				{
+					replacements = Replacements;
+				}
+
+				var r = GetReplacementInfo (replacements);
+				
+				// Process file with error handling
+				using (var i = File.OpenText (SourceFile.ItemSpec))
+				using (var o = File.CreateText (DestinationFile.ItemSpec))
+				{
+					string line;
+					while ((line = i.ReadLine ()) != null)
+					{
+						foreach (var e in r)
+						{
+							line = line.Replace (e.Key, e.Value);
+						}
+						o.WriteLine (line);
 					}
-					o.WriteLine (line);
 				}
-			}
 
-			return !Log.HasLoggedErrors;
+				return !Log.HasLoggedErrors;
+			}
+			catch (Exception ex)
+			{
+				Log.LogError ($"Task {nameof (ReplaceFileContents)} failed: {ex.Message}");
+				return false;
+			}
 		}
 
 		static  readonly    char[]  Separator   = new [] { '=' };
 
 		static Dictionary<string, string> GetReplacementInfo (string[] replacements)
 		{
-			var r   = new Dictionary<string, string> (replacements?.Length ?? 0);
-			if (replacements == null)
+			var r = new Dictionary<string, string> (replacements?.Length ?? 0);
+			if (replacements == null || replacements.Length == 0)
 				return r;
-			foreach (var e in replacements) {
+
+			foreach (var e in replacements)
+			{
 				if (string.IsNullOrEmpty (e))
 					continue;
+
 				var kvp = e.Split (Separator, 2, StringSplitOptions.RemoveEmptyEntries);
-				r.Add (kvp [0], kvp.Length > 1 ? kvp [1] : "");
+				
+				// Validate we have a key
+				if (kvp.Length == 0)
+				{
+					continue; // Skip malformed lines
+				}
+
+				string key = kvp[0];
+				string value = kvp.Length > 1 ? kvp[1] : "";
+				
+				// Warn if key already exists (duplicate replacement)
+				if (r.ContainsKey (key))
+				{
+					Log.LogWarning ($"Duplicate replacement key: '{key}'");
+					r[key] = value; // Override with latest
+				}
+				else
+				{
+					r.Add (key, value);
+				}
 			}
 			return r;
 		}