diff --git a/packages/server/src/main/java/software/uncharted/terarium/hmiserver/controller/dataservice/ProjectController.java b/packages/server/src/main/java/software/uncharted/terarium/hmiserver/controller/dataservice/ProjectController.java
index b030f465d5..41d8f13e05 100644
--- a/packages/server/src/main/java/software/uncharted/terarium/hmiserver/controller/dataservice/ProjectController.java
+++ b/packages/server/src/main/java/software/uncharted/terarium/hmiserver/controller/dataservice/ProjectController.java
@@ -51,6 +51,7 @@
 import software.uncharted.terarium.hmiserver.models.dataservice.project.ProjectAsset;
 import software.uncharted.terarium.hmiserver.models.dataservice.project.ProjectExport;
 import software.uncharted.terarium.hmiserver.models.permissions.PermissionRelationships;
+import software.uncharted.terarium.hmiserver.models.permissions.PermissionUser;
 import software.uncharted.terarium.hmiserver.security.Roles;
 import software.uncharted.terarium.hmiserver.service.ClientEventService;
 import software.uncharted.terarium.hmiserver.service.CurrentUserService;
@@ -928,10 +929,10 @@ public ResponseEntity<PermissionRelationships> getProjectPermissions(@PathVariab
 		try {
 			for (final RebacPermissionRelationship permissionRelationship : rebacProject.getPermissionRelationships()) {
 				if (permissionRelationship.getSubjectType().equals(Schema.Type.USER)) {
-					permissions.addUser(
-						reBACService.getUser(permissionRelationship.getSubjectId()),
-						permissionRelationship.getRelationship()
-					);
+					PermissionUser user = reBACService.getUser(permissionRelationship.getSubjectId());
+					if (user != null) {
+						permissions.addUser(user, permissionRelationship.getRelationship());
+					}
 				} else if (permissionRelationship.getSubjectType().equals(Schema.Type.GROUP)) {
 					permissions.addGroup(
 						reBACService.getGroup(permissionRelationship.getSubjectId()),
diff --git a/packages/server/src/main/java/software/uncharted/terarium/hmiserver/controller/permissions/GroupsController.java b/packages/server/src/main/java/software/uncharted/terarium/hmiserver/controller/permissions/GroupsController.java
index fea7e37c10..9077ba3aa8 100644
--- a/packages/server/src/main/java/software/uncharted/terarium/hmiserver/controller/permissions/GroupsController.java
+++ b/packages/server/src/main/java/software/uncharted/terarium/hmiserver/controller/permissions/GroupsController.java
@@ -61,7 +61,9 @@ public ResponseEntity<PermissionGroup> getGroup(@PathVariable("groupId") final S
 				for (final RebacPermissionRelationship permissionRelationship : relationships) {
 					if (permissionRelationship.getSubjectType().equals(Schema.Type.USER)) {
 						final PermissionUser user = reBACService.getUser(permissionRelationship.getSubjectId());
-						permissions.addUser(user, permissionRelationship.getRelationship());
+						if (user != null) {
+							permissions.addUser(user, permissionRelationship.getRelationship());
+						}
 					} else if (permissionRelationship.getSubjectType().equals(Schema.Type.GROUP)) {
 						final PermissionGroup group = reBACService.getGroup(permissionRelationship.getSubjectId());
 						permissions.addGroup(group, permissionRelationship.getRelationship());
diff --git a/packages/server/src/main/java/software/uncharted/terarium/hmiserver/service/data/ProjectPermissionsService.java b/packages/server/src/main/java/software/uncharted/terarium/hmiserver/service/data/ProjectPermissionsService.java
index 86bfba08c0..dff896a026 100644
--- a/packages/server/src/main/java/software/uncharted/terarium/hmiserver/service/data/ProjectPermissionsService.java
+++ b/packages/server/src/main/java/software/uncharted/terarium/hmiserver/service/data/ProjectPermissionsService.java
@@ -39,9 +39,11 @@ private List<Contributor> getContributorsByRelationships(
 			if (relationships.length == 0 || List.of(relationships).contains(relationship)) {
 				if (permissionRelationship.getSubjectType().equals(Schema.Type.USER)) {
 					final PermissionUser user = reBACService.getUser(permissionRelationship.getSubjectId());
-					final String name = user.getFirstName() + " " + user.getLastName();
-					if (!contributorMap.containsKey(name)) {
-						contributorMap.put(name, new Contributor(name, user.getId(), relationship));
+					if (user != null) {
+						final String name = user.getFirstName() + " " + user.getLastName();
+						if (!contributorMap.containsKey(name)) {
+							contributorMap.put(name, new Contributor(name, user.getId(), relationship));
+						}
 					}
 				} else if (permissionRelationship.getSubjectType().equals(Schema.Type.GROUP)) {
 					final PermissionGroup group = reBACService.getGroup(permissionRelationship.getSubjectId());
diff --git a/packages/server/src/main/java/software/uncharted/terarium/hmiserver/utils/rebac/ReBACService.java b/packages/server/src/main/java/software/uncharted/terarium/hmiserver/utils/rebac/ReBACService.java
index 11bd0beeef..af667b7de3 100644
--- a/packages/server/src/main/java/software/uncharted/terarium/hmiserver/utils/rebac/ReBACService.java
+++ b/packages/server/src/main/java/software/uncharted/terarium/hmiserver/utils/rebac/ReBACService.java
@@ -292,27 +292,32 @@ public PermissionUser getUser(final String id) {
 		final PermissionUser result = userCache.get(id, key_id -> {
 			final UsersResource usersResource = keycloak.realm(REALM_NAME).users();
 			final UserResource userResource = usersResource.get(key_id);
-			final UserRepresentation userRepresentation = userResource.toRepresentation();
-
-			final List<PermissionRole> roles = new ArrayList<>();
-			for (final RoleRepresentation roleRepresentation : userResource.roles().getAll().getRealmMappings()) {
-				if (roleRepresentation.getDescription().isBlank()) {
-					final PermissionRole role = new PermissionRole(
-						roleRepresentation.getId(),
-						roleRepresentation.getName()
-						// no users are acquired (to avoid circular references etc)
-					);
-					roles.add(role);
+			try {
+				final UserRepresentation userRepresentation = userResource.toRepresentation();
+
+				final List<PermissionRole> roles = new ArrayList<>();
+				for (final RoleRepresentation roleRepresentation : userResource.roles().getAll().getRealmMappings()) {
+					if (roleRepresentation.getDescription().isBlank()) {
+						final PermissionRole role = new PermissionRole(
+							roleRepresentation.getId(),
+							roleRepresentation.getName()
+							// no users are acquired (to avoid circular references etc)
+						);
+						roles.add(role);
+					}
 				}
-			}
 
-			return new PermissionUser(
-				userRepresentation.getId(),
-				userRepresentation.getFirstName(),
-				userRepresentation.getLastName(),
-				userRepresentation.getEmail(),
-				roles
-			);
+				return new PermissionUser(
+					userRepresentation.getId(),
+					userRepresentation.getFirstName(),
+					userRepresentation.getLastName(),
+					userRepresentation.getEmail(),
+					roles
+				);
+			} catch (Exception e) {
+				log.error("User identified by SpiceDB with id \"{}\" is not found in Keycloak.", id);
+				return null;
+			}
 		});
 		log.trace("User Cache hit: {}, miss: {}", userCache.stats().hitCount(), userCache.stats().missCount());
 		return result;