diff --git a/docs/changes/352.bugfix.md b/docs/changes/352.bugfix.md
new file mode 100644
index 00000000..7b828512
--- /dev/null
+++ b/docs/changes/352.bugfix.md
@@ -0,0 +1,5 @@
+# Bug fix: non-XGB jobs no longer probe XGB sidecar files (E4)
+
+XGB sidecar files (stereo and gamma-hadron) are now opened only when the active
+reconstruction method and gamma-hadron cut type actually require them, eliminating
+spurious ROOT file-open errors in non-XGB jobs.
diff --git a/inc/CData.h b/inc/CData.h
index b1cc9a72..380a01e1 100644
--- a/inc/CData.h
+++ b/inc/CData.h
@@ -30,6 +30,7 @@ class CData
         vector< double > fTelX;
         vector< double > fTelY;
         vector< double > fTelZ;
+        string fDataFileName;
 
         void reconstruct_3tel_images( long unsigned int );
         void reconstruct_3tel_images_direction();
@@ -280,6 +281,7 @@ class CData
         float get_Yoff( unsigned int method );
         void   initialize_xgb_tree();
         TTree* getXGBTree( string file_name, string suffix, string tree_name );
+        bool   loadGHXGBTree( string gh_suffix );
         pair<float, float> get_XYoff_derot( unsigned int method );
         virtual Long64_t LoadTree( Long64_t entry );
         float            get_GH_Gamma_Prediction();
diff --git a/src/CData.cpp b/src/CData.cpp
index 7bacdbad..ce7ee5b5 100644
--- a/src/CData.cpp
+++ b/src/CData.cpp
@@ -31,6 +31,7 @@ CData::CData( TTree* tree, bool bMC, bool bShort, string file_name, string stere
     fShort = bShort;
     fVersion = 6;
     fTelescopeCombination = 0;
+    fDataFileName = file_name;
     Init( tree );
 
     fStereoFriendTree = getXGBTree( file_name, stereo_suffix, "StereoAnalysis" );
@@ -1126,3 +1127,25 @@ void CData::initialize_xgb_tree()
         GH_Is_Gamma = false;
     }
 }
+
+/*
+ * Deferred loading of the XGB gamma-hadron friend tree.
+ * Call this after the analysis type is known (e.g. after readCuts()),
+ * when the caller has confirmed that XGB gamma-hadron cuts are active.
+ * Idempotent: a second call is a no-op if the tree is already loaded.
+ */
+bool CData::loadGHXGBTree( string gh_suffix )
+{
+    if( fGHFriendTree )
+    {
+        return true;
+    }
+    if( fDataFileName.empty() )
+    {
+        cout << "CData::loadGHXGBTree error: no data file name stored" << endl;
+        return false;
+    }
+    fGHFriendTree = getXGBTree( fDataFileName, gh_suffix, "Classification" );
+    initialize_xgb_tree();
+    return ( fGHFriendTree != 0 );
+}
diff --git a/src/VStereoAnalysis.cpp b/src/VStereoAnalysis.cpp
index 3147257f..8cbe4212 100644
--- a/src/VStereoAnalysis.cpp
+++ b/src/VStereoAnalysis.cpp
@@ -348,6 +348,14 @@ double VStereoAnalysis::fillHistograms( int icounter, int irun, double iAzMin, d
     // initialize cuts
     setCuts( fRunPara->fRunList[fHisCounter], irun );
 
+    // load XGB gamma-hadron friend tree now that the analysis type is known
+    if( fCuts && fCuts->useXGBoostCuts()
+            && fDataRun
+            && !fRunPara->fXGB_gh_file_suffix.empty() )
+    {
+        fDataRun->loadGHXGBTree( fRunPara->fXGB_gh_file_suffix );
+    }
+
     // define histograms
     fDirTotRun[fHisCounter]->cd();
     fHisto[fHisCounter]->setRunNumber( irun );
@@ -1967,8 +1975,9 @@ CData* VStereoAnalysis::getDataFromFile( int i_runNumber )
             false,
             false,
             iFileName,
-            fRunPara->fXGB_stereo_file_suffix,
-            fRunPara->fXGB_gh_file_suffix
+            ( fRunPara->fEnergyReconstructionMethod == 2 || fRunPara->fDirectionReconstructionMethod == 2 )
+                ? fRunPara->fXGB_stereo_file_suffix : "",
+            ""  // GH XGB tree loaded later, after analysis type is known from cut file
         );
         // read current (major) epoch from data file
         VEvndispRunParameter* i_runPara = ( VEvndispRunParameter* )fDataFile->Get( "runparameterV2" );
diff --git a/src/makeEffectiveArea.cpp b/src/makeEffectiveArea.cpp
index 5d1cede1..d29f4665 100644
--- a/src/makeEffectiveArea.cpp
+++ b/src/makeEffectiveArea.cpp
@@ -180,7 +180,11 @@ int main( int argc, char* argv[] )
         exit( EXIT_FAILURE );
     }
 
-    CData d( c, true, false, fRunPara->fdatafile, fRunPara->fXGB_stereo_file_suffix, fRunPara->fXGB_gh_file_suffix );
+    const bool i_need_stereo_xgb = ( fRunPara->fEnergyReconstructionMethod == 2
+                                        || fRunPara->fDirectionReconstructionMethod == 2 );
+    CData d( c, true, false, fRunPara->fdatafile,
+             i_need_stereo_xgb ? fRunPara->fXGB_stereo_file_suffix : "",
+             fCuts->useXGBoostCuts() ? fRunPara->fXGB_gh_file_suffix : "" );
     d.initialize_3tel_reconstruction(
         fRunPara->fRerunStereoReconstruction_3telescopes,
         fRunPara->fRerunStereoReconstruction_minAngle,