diff --git a/MdeModulePkg/Bus/Pci/NvmExpressDxe/NvmExpressHci.c b/MdeModulePkg/Bus/Pci/NvmExpressDxe/NvmExpressHci.c
index 5eb9d922fd..4e9831c72b 100644
--- a/MdeModulePkg/Bus/Pci/NvmExpressDxe/NvmExpressHci.c
+++ b/MdeModulePkg/Bus/Pci/NvmExpressDxe/NvmExpressHci.c
@@ -30,8 +30,10 @@ UINTN  mNvmeControllerNumber = 0;
 **/
 EFI_STATUS
 ReadNvmeControllerCapabilities (
-  IN NVME_CONTROLLER_PRIVATE_DATA  *Private,
-  IN NVME_CAP                      *Cap
+  // MU_CHANGE [BEGIN] - Correct Cap parameter modifier
+  IN  NVME_CONTROLLER_PRIVATE_DATA  *Private,
+  OUT NVME_CAP                      *Cap
+  // MU_CHANGE [END] - Correct Cap parameter modifier
   )
 {
   EFI_PCI_IO_PROTOCOL  *PciIo;
@@ -743,13 +745,36 @@ NvmeControllerInit (
   NVME_AQA             Aqa;
   NVME_ASQ             Asq;
   NVME_ACQ             Acq;
+  UINT16               VidDid[2]; // MU_CHANGE - Improve NVMe controller init robustness
   UINT8                Sn[21];
   UINT8                Mn[41];
 
+  // MU_CHANGE [BEGIN] - Improve NVMe controller init robustness
+  PciIo = Private->PciIo;
+
+  //
+  // Verify the controller is still accessible
+  //
+  Status = PciIo->Pci.Read (
+                        PciIo,
+                        EfiPciIoWidthUint16,
+                        PCI_VENDOR_ID_OFFSET,
+                        ARRAY_SIZE (VidDid),
+                        VidDid
+                        );
+  if (EFI_ERROR (Status)) {
+    ASSERT_EFI_ERROR (Status);
+    return EFI_DEVICE_ERROR;
+  }
+
+  if ((VidDid[0] == 0xFFFF) || (VidDid[1] == 0xFFFF)) {
+    return EFI_DEVICE_ERROR;
+  }
+
   //
   // Enable this controller.
   //
-  PciIo  = Private->PciIo;
+  // MU_CHANGE [END] - Improve NVMe controller init robustness
   Status = PciIo->Attributes (
                     PciIo,
                     EfiPciIoAttributeOperationSupported,
@@ -788,7 +813,17 @@ NvmeControllerInit (
   //
   // Currently the driver only supports 4k page size.
   //
-  ASSERT ((Private->Cap.Mpsmin + 12) <= EFI_PAGE_SHIFT);
+
+  // MU_CHANGE [BEGIN] - Improve NVMe controller init robustness
+
+  // Currently, this means Cap.Mpsmin must be zero for an EFI_PAGE_SHIFT size of 12.
+  // ASSERT ((Private->Cap.Mpsmin + 12) <= EFI_PAGE_SHIFT);
+  if ((Private->Cap.Mpsmin + 12) > EFI_PAGE_SHIFT) {
+    DEBUG ((DEBUG_ERROR, "NvmeControllerInit: Mpsmin is larger than expected (0x%02x).\n", Private->Cap.Mpsmin));
+    return EFI_DEVICE_ERROR;
+  }
+
+  // MU_CHANGE [END] - Improve NVMe controller init robustness
 
   Private->Cid[0]        = 0;
   Private->Cid[1]        = 0;
diff --git a/MdePkg/Include/IndustryStandard/Nvme.h b/MdePkg/Include/IndustryStandard/Nvme.h
index d1a7b683a0..c494194813 100644
--- a/MdePkg/Include/IndustryStandard/Nvme.h
+++ b/MdePkg/Include/IndustryStandard/Nvme.h
@@ -52,23 +52,25 @@
 //
 // 3.1.1 Offset 00h: CAP - Controller Capabilities
 //
+// MU_CHANGE [BEGIN] - Add missing capability descriptions
 typedef struct {
   UINT16    Mqes;       // Maximum Queue Entries Supported
   UINT8     Cqr    : 1; // Contiguous Queues Required
   UINT8     Ams    : 2; // Arbitration Mechanism Supported
   UINT8     Rsvd1  : 5;
-  UINT8     To;     // Timeout
-  UINT16    Dstrd  : 4;
+  UINT8     To;         // Timeout
+  UINT16    Dstrd  : 4; // Doorbell Stride
   UINT16    Nssrs  : 1; // NVM Subsystem Reset Supported NSSRS
   UINT16    Css    : 8; // Command Sets Supported - Bit 37
   UINT16    Bps    : 1; // Boot Partition Support - Bit 45 in NVMe1.4
   UINT16    Rsvd3  : 2;
-  UINT8     Mpsmin : 4;
-  UINT8     Mpsmax : 4;
-  UINT8     Pmrs   : 1;
-  UINT8     Cmbs   : 1;
+  UINT8     Mpsmin : 4; // Memory Page Size Minimum
+  UINT8     Mpsmax : 4; // Memory Page Size Maximum
+  UINT8     Pmrs   : 1; // Persistent Memory Region Supported
+  UINT8     Cmbs   : 1; // Controller Memory Buffer Supported
   UINT8     Rsvd4  : 6;
 } NVME_CAP;
+// MU_CHANGE [END] - Add missing capability descriptions
 
 //
 // 3.1.2 Offset 08h: VS - Version