diff --git a/Configuration/Eras/python/Era_Phase2C8_cff.py b/Configuration/Eras/python/Era_Phase2C8_cff.py
new file mode 100644
index 0000000000000..3274c863157ae
--- /dev/null
+++ b/Configuration/Eras/python/Era_Phase2C8_cff.py
@@ -0,0 +1,7 @@
+import FWCore.ParameterSet.Config as cms
+
+from Configuration.Eras.Era_Phase2C4_cff import Phase2C4
+from Configuration.Eras.Modifier_phase2_hgcalV10_cff import phase2_hgcalV10
+
+Phase2C8 = cms.ModifierChain(Phase2C4, phase2_hgcalV10)
+
diff --git a/Configuration/Eras/python/Era_Phase2C8_timing_cff.py b/Configuration/Eras/python/Era_Phase2C8_timing_cff.py
new file mode 100644
index 0000000000000..1eae0f72d44c3
--- /dev/null
+++ b/Configuration/Eras/python/Era_Phase2C8_timing_cff.py
@@ -0,0 +1,7 @@
+import FWCore.ParameterSet.Config as cms
+
+from Configuration.Eras.Era_Phase2C8_cff import Phase2C8
+from Configuration.Eras.Modifier_phase2_timing_cff import phase2_timing
+
+Phase2C8_timing = cms.ModifierChain(Phase2C8, phase2_timing)
+
diff --git a/Configuration/Eras/python/Era_Phase2C8_timing_layer_bar_cff.py b/Configuration/Eras/python/Era_Phase2C8_timing_layer_bar_cff.py
new file mode 100644
index 0000000000000..d36c9c071bd1b
--- /dev/null
+++ b/Configuration/Eras/python/Era_Phase2C8_timing_layer_bar_cff.py
@@ -0,0 +1,8 @@
+import FWCore.ParameterSet.Config as cms
+
+from Configuration.Eras.Era_Phase2C8_timing_cff import Phase2C8_timing
+from Configuration.Eras.Modifier_phase2_timing_layer_cff import phase2_timing_layer
+from Configuration.Eras.Modifier_phase2_timing_layer_bar_cff import phase2_timing_layer_bar
+
+Phase2C8_timing_layer_bar = cms.ModifierChain(Phase2C8_timing, phase2_timing_layer, phase2_timing_layer_bar)
+
diff --git a/Configuration/Eras/python/Modifier_phase2_hgcalV10_cff.py b/Configuration/Eras/python/Modifier_phase2_hgcalV10_cff.py
new file mode 100644
index 0000000000000..bf6e4affd9b43
--- /dev/null
+++ b/Configuration/Eras/python/Modifier_phase2_hgcalV10_cff.py
@@ -0,0 +1,6 @@
+import FWCore.ParameterSet.Config as cms
+
+# This modifier is for HGCal V10 geometry-specific changes for sim, reco, etc.
+
+phase2_hgcalV10 =  cms.Modifier()
+
diff --git a/Configuration/Geometry/python/dict2023Geometry.py b/Configuration/Geometry/python/dict2023Geometry.py
index 557e8db872290..67f58079ee220 100644
--- a/Configuration/Geometry/python/dict2023Geometry.py
+++ b/Configuration/Geometry/python/dict2023Geometry.py
@@ -425,7 +425,7 @@
             'from Geometry.EcalMapping.EcalMapping_cfi import *',
             'from Geometry.EcalMapping.EcalMappingRecord_cfi import *',
         ],
-        "era" : "run2_HE_2017, run2_HF_2017, run2_HCAL_2017, run3_HB, phase2_hcal, phase2_hgcal, hcalHardcodeConditions, hcalSkipPacker",
+        "era" : "run2_HE_2017, run2_HF_2017, run2_HCAL_2017, run3_HB, phase2_hcal, phase2_hgcal, phase2_hgcalV9, hcalHardcodeConditions, hcalSkipPacker",
     },
 
     "C5" : {
@@ -500,7 +500,7 @@
             'from Geometry.EcalMapping.EcalMapping_cfi import *',
             'from Geometry.EcalMapping.EcalMappingRecord_cfi import *',
         ],
-        "era" : "run2_HE_2017, run2_HF_2017, run2_HCAL_2017, run3_HB, phase2_hcal, phase2_hgcal, hcalHardcodeConditions, hcalSkipPacker",
+        "era" : "run2_HE_2017, run2_HF_2017, run2_HCAL_2017, run3_HB, phase2_hcal, phase2_hgcal, phase2_hgcalV9, hcalHardcodeConditions, hcalSkipPacker",
     },
 
     "C6" : {
@@ -586,7 +586,7 @@
             'from Geometry.EcalMapping.EcalMapping_cfi import *',
             'from Geometry.EcalMapping.EcalMappingRecord_cfi import *',
         ],
-        "era" : "run2_HE_2017, run2_HF_2017, run2_HCAL_2017, run3_HB, phase2_hcal, phase2_hgcal, hcalHardcodeConditions, hcalSkipPacker, phase2_hfnose",
+        "era" : "run2_HE_2017, run2_HF_2017, run2_HCAL_2017, run3_HB, phase2_hcal, phase2_hgcal, phase2_hgcalV9, hcalHardcodeConditions, hcalSkipPacker, phase2_hfnose",
     },
 
     "C7" : {
@@ -661,7 +661,7 @@
             'from Geometry.EcalMapping.EcalMapping_cfi import *',
             'from Geometry.EcalMapping.EcalMappingRecord_cfi import *',
         ],
-        "era" : "run2_HE_2017, run2_HF_2017, run2_HCAL_2017, run3_HB, phase2_hcal, phase2_hgcal, hcalHardcodeConditions, hcalSkipPacker",
+        "era" : "run2_HE_2017, run2_HF_2017, run2_HCAL_2017, run3_HB, phase2_hcal, phase2_hgcal, phase2_hgcalV9, hcalHardcodeConditions, hcalSkipPacker",
     },
 
     "C8" : {
@@ -735,7 +735,7 @@
             'from Geometry.EcalMapping.EcalMapping_cfi import *',
             'from Geometry.EcalMapping.EcalMappingRecord_cfi import *',
         ],
-        "era" : "run2_HE_2017, run2_HF_2017, run2_HCAL_2017, run3_HB, phase2_hcal, phase2_hgcal, hcalHardcodeConditions, hcalSkipPacker",
+        "era" : "run2_HE_2017, run2_HF_2017, run2_HCAL_2017, run3_HB, phase2_hcal, phase2_hgcal, phase2_hgcalV9, phase2_hgcalV10, hcalHardcodeConditions, hcalSkipPacker",
     },
 
 }
diff --git a/Configuration/PyReleaseValidation/python/upgradeWorkflowComponents.py b/Configuration/PyReleaseValidation/python/upgradeWorkflowComponents.py
index 4a9e80f350080..f4cc0c2577f4f 100644
--- a/Configuration/PyReleaseValidation/python/upgradeWorkflowComponents.py
+++ b/Configuration/PyReleaseValidation/python/upgradeWorkflowComponents.py
@@ -428,7 +428,7 @@
         'Geom' : 'Extended2023D41',
         'HLTmenu': '@fake2',
         'GT' : 'auto:phase2_realistic',
-        'Era' : 'Phase2C4_timing_layer_bar',
+        'Era' : 'Phase2C8_timing_layer_bar',
         'ScenToRun' : ['GenSimHLBeamSpotFull','DigiFullTrigger','RecoFullGlobal', 'HARVESTFullGlobal'],
     },
 }
diff --git a/Configuration/StandardSequences/python/Eras.py b/Configuration/StandardSequences/python/Eras.py
index 05121459254e8..22447eac87524 100644
--- a/Configuration/StandardSequences/python/Eras.py
+++ b/Configuration/StandardSequences/python/Eras.py
@@ -42,6 +42,9 @@ def __init__(self):
                  'Phase2C6',
                  'Phase2C6_timing',
                  'Phase2C4_timing_layer_bar',
+                 'Phase2C8',
+                 'Phase2C8_timing',
+                 'Phase2C8_timing_layer_bar',
         ]
 
         internalUseMods = ['run2_common', 'run2_25ns_specific',
@@ -54,7 +57,7 @@ def __init__(self):
                            'phase1Pixel', 'run3_GEM', 'run2_GEM_2017',
                            'run2_CSC_2018',
                            'phase2_common', 'phase2_tracker',
-                           'phase2_hgcal', 'phase2_muon', 'phase2_timing', 'phase2_hgcalV9', 'phase2_hfnose', 
+                           'phase2_hgcal', 'phase2_muon', 'phase2_timing', 'phase2_hgcalV9', 'phase2_hfnose', 'phase2_hgcalV10',
                            'phase2_timing_layer','phase2_timing_layer_tile','phase2_timing_layer_bar','phase2_hcal',
                            'trackingLowPU', 'trackingPhase1', 'ctpps_2016', 'trackingPhase2PU140','highBetaStar_2018',
                            'tracker_apv_vfp30_2016', 'pf_badHcalMitigation', 'run2_miniAOD_80XLegacy','run2_miniAOD_94XFall17', 'run2_nanoAOD_92X',