diff --git a/common/error_code.h b/common/error_code.h
index 7d9cfff..a889888 100644
--- a/common/error_code.h
+++ b/common/error_code.h
@@ -86,6 +86,7 @@
   kNotEnoughSpace = 60,
   kDeviceCorrupted = 61,
   kPackageExcludedFromUpdate = 62,
+  kPostInstallMountError = 63,
 
   // VERY IMPORTANT! When adding new error codes:
   //
diff --git a/common/error_code_utils.cc b/common/error_code_utils.cc
index cda4c7e..421544a 100644
--- a/common/error_code_utils.cc
+++ b/common/error_code_utils.cc
@@ -173,6 +173,8 @@
       return "ErrorCode::kDeviceCorrupted";
     case ErrorCode::kPackageExcludedFromUpdate:
       return "ErrorCode::kPackageExcludedFromUpdate";
+    case ErrorCode::kPostInstallMountError:
+      return "ErrorCode::kPostInstallMountError";
       // Don't add a default case to let the compiler warn about newly added
       // error codes which should be added here.
   }
diff --git a/metrics_utils.cc b/metrics_utils.cc
index 2211a67..a947a7e 100644
--- a/metrics_utils.cc
+++ b/metrics_utils.cc
@@ -95,6 +95,7 @@
     case ErrorCode::kPostinstallRunnerError:
     case ErrorCode::kPostinstallBootedFromFirmwareB:
     case ErrorCode::kPostinstallFirmwareRONotUpdatable:
+    case ErrorCode::kPostInstallMountError:
       return metrics::AttemptResult::kPostInstallFailed;
 
     case ErrorCode::kUserCanceled:
@@ -189,6 +190,7 @@
     case ErrorCode::kOmahaResponseHandlerError:
     case ErrorCode::kFilesystemCopierError:
     case ErrorCode::kPostinstallRunnerError:
+    case ErrorCode::kPostInstallMountError:
     case ErrorCode::kPayloadMismatchedType:
     case ErrorCode::kInstallDeviceOpenError:
     case ErrorCode::kKernelDeviceOpenError:
diff --git a/payload_consumer/postinstall_runner_action.cc b/payload_consumer/postinstall_runner_action.cc
index 91c3a64..d51241f 100644
--- a/payload_consumer/postinstall_runner_action.cc
+++ b/payload_consumer/postinstall_runner_action.cc
@@ -56,8 +56,22 @@
 
 void PostinstallRunnerAction::PerformAction() {
   CHECK(HasInputObject());
+  CHECK(boot_control_);
   install_plan_ = GetInputObject();
 
+  auto dynamic_control = boot_control_->GetDynamicPartitionControl();
+  CHECK(dynamic_control);
+
+  // Mount snapshot partitions for Virtual AB Compression Compression.
+  if (dynamic_control->GetVirtualAbCompressionFeatureFlag().IsEnabled()) {
+    // Before calling MapAllPartitions to map snapshot devices, all CowWriters
+    // must be closed, and MapAllPartitions() should be called.
+    dynamic_control->UnmapAllPartitions();
+    if (!dynamic_control->MapAllPartitions()) {
+      return CompletePostinstall(ErrorCode::kPostInstallMountError);
+    }
+  }
+
   // We always powerwash when rolling back, however policy can determine
   // if this is a full/normal powerwash, or a special rollback powerwash
   // that retains a small amount of system state such as enrollment and