Index: Riskeer/Storage/src/Riskeer.Storage.Core/SafeFileWriter.cs
===================================================================
diff -u -re35fa47ac631890035c1e409fbc0c63f03fd90ae -r1fda4b3e872d21504101e9af5077095f2b318a53
--- Riskeer/Storage/src/Riskeer.Storage.Core/SafeFileWriter.cs	(.../SafeFileWriter.cs)	(revision e35fa47ac631890035c1e409fbc0c63f03fd90ae)
+++ Riskeer/Storage/src/Riskeer.Storage.Core/SafeFileWriter.cs	(.../SafeFileWriter.cs)	(revision 1fda4b3e872d21504101e9af5077095f2b318a53)
@@ -113,6 +113,8 @@
                 {
                     isTemporaryFileEmpty = false;
 
+                    ThrowWhenTargetFileIsReadonly();
+
                     File.Move(targetFilePath, temporaryFilePath);
 
                     temporaryFileStream = File.Open(temporaryFilePath, FileMode.Open, FileAccess.ReadWrite, FileShare.Read);
@@ -153,5 +155,10 @@
 
             File.Delete(temporaryFilePath);
         }
+
+        private void ThrowWhenTargetFileIsReadonly()
+        {
+            using (File.Open(targetFilePath, FileMode.Open, FileAccess.ReadWrite, FileShare.Read)) {}
+        }
     }
 }
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