diff --git a/data_safe_haven/commands/sre.py b/data_safe_haven/commands/sre.py
index 8c3e0b5cdc..2cccfb90d0 100644
--- a/data_safe_haven/commands/sre.py
+++ b/data_safe_haven/commands/sre.py
@@ -50,6 +50,7 @@ def deploy(
         pulumi_config = DSHPulumiConfig.from_remote_or_create(
             context, encrypted_key=None, projects={}
         )
+
         sre_config = SREConfig.from_remote_by_name(context, name)
 
         # Check whether current IP address is authorised to take administrator actions
@@ -68,6 +69,7 @@ def deploy(
             pulumi_config=pulumi_config,
             create_project=True,
         )
+
         # Set Azure options
         stack.add_option(
             "azure-native:location", sre_config.azure.location, replace=False
diff --git a/data_safe_haven/infrastructure/project_manager.py b/data_safe_haven/infrastructure/project_manager.py
index eca352b28b..5153a74a54 100644
--- a/data_safe_haven/infrastructure/project_manager.py
+++ b/data_safe_haven/infrastructure/project_manager.py
@@ -119,27 +119,45 @@ def stack(self) -> automation.Stack:
         """Load the Pulumi stack, creating if needed."""
         if not self._stack:
             self.logger.debug(f"Creating/loading stack [green]{self.stack_name}[/].")
+            # Note: `create_or_select_stack` is not used here because we need to know whether the stack exists or not.
+            # There is no way to check if a stack exists other than trying to `create_stack` or `select_stack` and catching the error.
+            # `create_or_select_stack` never generates an error, and doesn't tell us whether the stack was created or selected.
+            # When creating a stack, it generates a new encryption key rather than using the project's key, so we need to set the key
+            # manually after creating the stack.
             try:
-                self._stack = automation.create_or_select_stack(
+                self._stack = automation.select_stack(
                     opts=automation.LocalWorkspaceOptions(
                         env_vars=self.account.env,
                         project_settings=self.project_settings,
-                        secrets_provider=self.context.pulumi_secrets_provider_url,
                         stack_settings={self.stack_name: self.stack_settings},
+                        secrets_provider=self.context.pulumi_secrets_provider_url,
                     ),
                     program=self.program,
                     project_name=self.project_name,
                     stack_name=self.stack_name,
                 )
-                self.logger.info(f"Loaded stack [green]{self.stack_name}[/].")
-                # Ensure encrypted key is stored in the Pulumi configuration
-                self.update_dsh_pulumi_encrypted_key(self._stack.workspace)
-                # Ensure workspace plugins are installed
-                self.install_plugins(self._stack.workspace)
-            except automation.CommandError as exc:
-                self.log_exception(exc)
-                msg = f"Could not load Pulumi stack {self.stack_name}."
-                raise DataSafeHavenPulumiError(msg) from exc
+            except automation.CommandError:
+                try:
+                    self._stack = automation.create_stack(
+                        opts=automation.LocalWorkspaceOptions(
+                            env_vars=self.account.env,
+                            project_settings=self.project_settings,
+                            secrets_provider=self.context.pulumi_secrets_provider_url,
+                        ),
+                        program=self.program,
+                        project_name=self.project_name,
+                        stack_name=self.stack_name,
+                    )
+                    self._stack.workspace.save_stack_settings(
+                        self.stack_name, self.stack_settings
+                    )
+                except automation.CommandError as exc:
+                    self.log_exception(exc)
+                    msg = f"Could not create Pulumi stack {self.stack_name}."
+                    raise DataSafeHavenPulumiError(msg) from exc
+            self.logger.info(f"Loaded stack [green]{self.stack_name}[/].")
+            # Ensure workspace plugins are installed
+            self.install_plugins(self._stack.workspace)
         return self._stack
 
     def add_option(self, name: str, value: str, *, replace: bool) -> None:
@@ -425,16 +443,6 @@ def update_dsh_pulumi_project(self) -> None:
         }
         self.pulumi_project.stack_config = all_config_dict
 
-    def update_dsh_pulumi_encrypted_key(self, workspace: automation.Workspace) -> None:
-        """Update encrypted key in the DSHPulumiProject object"""
-        stack_key = workspace.stack_settings(stack_name=self.stack_name).encrypted_key
-
-        if not self.pulumi_config.encrypted_key:
-            self.pulumi_config.encrypted_key = stack_key
-        elif self.pulumi_config.encrypted_key != stack_key:
-            msg = "Stack encrypted key does not match project encrypted key"
-            raise DataSafeHavenPulumiError(msg)
-
 
 class SREProjectManager(ProjectManager):
     """Interact with an SRE using Pulumi"""