diff --git a/LibNoDaveConnectionLibrary/DataTypes/Blocks/Step7V5/S7FunctionBlockRow.cs b/LibNoDaveConnectionLibrary/DataTypes/Blocks/Step7V5/S7FunctionBlockRow.cs
index 8dd0f92d..4c8b361b 100644
--- a/LibNoDaveConnectionLibrary/DataTypes/Blocks/Step7V5/S7FunctionBlockRow.cs
+++ b/LibNoDaveConnectionLibrary/DataTypes/Blocks/Step7V5/S7FunctionBlockRow.cs
@@ -781,9 +781,12 @@ public string ToString(bool useSymbol, bool addSemicolonAfterCommand, bool useDa
                         }
                         else
                         {
-                            par = "\"" + sym.Symbol + "\"." + paras[1];
-                            if (hasBit)
-                                par += "." + paras[2];
+                            if (sym != null)
+                            {
+                                par = "\"" + sym.Symbol + "\"." + paras[1];
+                                if (hasBit)
+                                    par += "." + paras[2];
+                            }
                         }
                     }
                 }
diff --git a/LibNoDaveConnectionLibrary/DataTypes/Projectfolders/Step7V5/BlocksOfflineFolder.cs b/LibNoDaveConnectionLibrary/DataTypes/Projectfolders/Step7V5/BlocksOfflineFolder.cs
index c74c0d4b..84c588ae 100644
--- a/LibNoDaveConnectionLibrary/DataTypes/Projectfolders/Step7V5/BlocksOfflineFolder.cs
+++ b/LibNoDaveConnectionLibrary/DataTypes/Projectfolders/Step7V5/BlocksOfflineFolder.cs
@@ -660,7 +660,14 @@ public Block GetBlock(ProjectBlockInfo blkInfo, S7ConvertingOptions myConvOpt)
 
                         retVal.AWLCode = MC7toAWL.GetAWL(0, myTmpBlk.mc7code.Length - 2, (int)myConvOpt.Mnemonic, myTmpBlk.mc7code, Networks, ParaList, prgFld, retVal, retVal.Parameter);
 
-                        retVal.AWLCode = JumpMarks.AddJumpmarks(retVal.AWLCode, myTmpBlk.jumpmarks, myTmpBlk.nwinfo, myConvOpt);
+                        try
+                        {
+                            retVal.AWLCode = JumpMarks.AddJumpmarks(retVal.AWLCode, myTmpBlk.jumpmarks, myTmpBlk.nwinfo, myConvOpt);
+                        }
+                        catch
+                        {
+                            //If the Jumpmarks are not valid, then just ignore them (eg. blocks written in C)
+                        }
 
                         LocalDataConverter.ConvertLocaldataToSymbols(retVal, myConvOpt);