diff --git a/src/NzbDrone.Common/Processes/ProcessProvider.cs b/src/NzbDrone.Common/Processes/ProcessProvider.cs
index 49e61c621..0ddab771f 100644
--- a/src/NzbDrone.Common/Processes/ProcessProvider.cs
+++ b/src/NzbDrone.Common/Processes/ProcessProvider.cs
@@ -8,6 +8,7 @@ using System.IO;
 using System.Linq;
 using NLog;
 using NzbDrone.Common.EnvironmentInfo;
+using NzbDrone.Common.Extensions;
 using NzbDrone.Common.Model;
 
 namespace NzbDrone.Common.Processes
@@ -129,7 +130,25 @@ namespace NzbDrone.Common.Processes
             {
                 foreach (DictionaryEntry environmentVariable in environmentVariables)
                 {
-                    startInfo.EnvironmentVariables.Add(environmentVariable.Key.ToString(), environmentVariable.Value.ToString());
+                    try
+                    {
+                        _logger.Trace("Setting environment variable '{0}' to '{1}'", environmentVariable.Key, environmentVariable.Value);
+                        startInfo.EnvironmentVariables.Add(environmentVariable.Key.ToString(), environmentVariable.Value.ToString());
+                    }
+                    catch (Exception e)
+                    {
+                        if (environmentVariable.Value == null)
+                        {
+                            _logger.Error(e, "Unable to set environment variable '{0}', value is null", environmentVariable.Key);
+                        }
+
+                        else
+                        {
+                            _logger.Error(e, "Unable to set environment variable '{0}'", environmentVariable.Key);
+                        }
+
+                        throw;
+                    }
                 }
             }
 
diff --git a/src/NzbDrone.Core/Notifications/CustomScript/CustomScript.cs b/src/NzbDrone.Core/Notifications/CustomScript/CustomScript.cs
index 4686ed939..d29c956ee 100644
--- a/src/NzbDrone.Core/Notifications/CustomScript/CustomScript.cs
+++ b/src/NzbDrone.Core/Notifications/CustomScript/CustomScript.cs
@@ -40,7 +40,7 @@ namespace NzbDrone.Core.Notifications.CustomScript
             environmentVariables.Add("Sonarr_Series_Title", series.Title);
             environmentVariables.Add("Sonarr_Series_TvdbId", series.TvdbId.ToString());
             environmentVariables.Add("Sonarr_Series_TvMazeId", series.TvMazeId.ToString());
-            environmentVariables.Add("Sonarr_Series_ImdbId", series.ImdbId);
+            environmentVariables.Add("Sonarr_Series_ImdbId", series.ImdbId ?? string.Empty);
             environmentVariables.Add("Sonarr_Series_Type", series.SeriesType.ToString());
             environmentVariables.Add("Sonarr_Release_EpisodeCount", remoteEpisode.Episodes.Count.ToString());
             environmentVariables.Add("Sonarr_Release_SeasonNumber", remoteEpisode.ParsedEpisodeInfo.SeasonNumber.ToString());
@@ -72,7 +72,7 @@ namespace NzbDrone.Core.Notifications.CustomScript
             environmentVariables.Add("Sonarr_Series_Path", series.Path);
             environmentVariables.Add("Sonarr_Series_TvdbId", series.TvdbId.ToString());
             environmentVariables.Add("Sonarr_Series_TvMazeId", series.TvMazeId.ToString());
-            environmentVariables.Add("Sonarr_Series_ImdbId", series.ImdbId);
+            environmentVariables.Add("Sonarr_Series_ImdbId", series.ImdbId ?? string.Empty);
             environmentVariables.Add("Sonarr_Series_Type", series.SeriesType.ToString());
             environmentVariables.Add("Sonarr_EpisodeFile_Id", episodeFile.Id.ToString());
             environmentVariables.Add("Sonarr_EpisodeFile_EpisodeCount", episodeFile.Episodes.Value.Count.ToString());
@@ -109,7 +109,7 @@ namespace NzbDrone.Core.Notifications.CustomScript
             environmentVariables.Add("Sonarr_Series_Path", series.Path);
             environmentVariables.Add("Sonarr_Series_TvdbId", series.TvdbId.ToString());
             environmentVariables.Add("Sonarr_Series_TvMazeId", series.TvMazeId.ToString());
-            environmentVariables.Add("Sonarr_Series_ImdbId", series.ImdbId);
+            environmentVariables.Add("Sonarr_Series_ImdbId", series.ImdbId ?? string.Empty);
             environmentVariables.Add("Sonarr_Series_Type", series.SeriesType.ToString());
 
             ExecuteScript(environmentVariables);