diff --git a/src/main/java/cz/cvut/kbss/study/model/Role.java b/src/main/java/cz/cvut/kbss/study/model/Role.java
index 988cbe26..700b7734 100644
--- a/src/main/java/cz/cvut/kbss/study/model/Role.java
+++ b/src/main/java/cz/cvut/kbss/study/model/Role.java
@@ -3,11 +3,12 @@
 import com.fasterxml.jackson.annotation.JsonValue;
 import cz.cvut.kbss.jopa.model.annotations.Individual;
 import cz.cvut.kbss.study.security.SecurityConstants;
+import java.util.Optional;
 
 public enum Role {
 
     // TODO deprecated -- should be removed.
-    @Individual(iri=Vocabulary.s_i_RM_ADMIN)
+    @Individual(iri = Vocabulary.s_i_RM_ADMIN)
     administrator(SecurityConstants.ROLE_ADMIN, Vocabulary.s_i_RM_ADMIN),
     // TODO deprecated -- should be removed.
     @Individual(iri = Vocabulary.s_i_RM_USER)
@@ -44,7 +45,7 @@ public enum Role {
     rejectRecords(SecurityConstants.rejectRecords, Vocabulary.s_i_reject_records_role),
 
     @Individual(iri = Vocabulary.s_i_publish_records_role)
-    publishRecords(SecurityConstants.publishRecords ,Vocabulary.s_i_publish_records_role),
+    publishRecords(SecurityConstants.publishRecords, Vocabulary.s_i_publish_records_role),
 
     @Individual(iri = Vocabulary.s_i_import_codelists_role)
     importCodelists(SecurityConstants.importCodelists, Vocabulary.s_i_import_codelists_role);
@@ -59,7 +60,7 @@ public enum Role {
     }
 
     @JsonValue
-    public String getRoleName(){
+    public String getRoleName() {
         return roleName;
     }
 
@@ -68,52 +69,60 @@ public String getIri() {
     }
 
     /**
-     * Returns {@link Role} with the specified IRI.
+     * Retrieves a role based on its IRI.
      *
-     * @param iri role identifier
-     * @return matching {@code Role}
-     * @throws IllegalArgumentException When no matching role is found
+     * <p>This method iterates over all available roles and checks if any role's IRI
+     * matches the provided IRI string. If a match is found, the corresponding role
+     * is returned as an Optional. If no match is found, an empty Optional is returned.</p>
+     *
+     * @param iri the IRI of the role to retrieve
+     * @return an Optional containing the corresponding Role if found,
+     * or an empty Optional if no matching role exists
      */
-    public static Role fromIri(String iri) {
+    public static Optional<Role> fromIri(String iri) {
         for (Role r : values()) {
             if (r.getIri().equals(iri)) {
-                return r;
+                return Optional.of(r);
             }
         }
-        throw new IllegalArgumentException("Unknown role identifier '" + iri + "'.");
+        return Optional.empty();
     }
 
     /**
-     * Returns {@link Role} with the specified constant name.
+     * Retrieves a role based on its role name.
+     *
+     * <p>This method iterates over all available roles and checks if any role's
+     * name matches the provided name string (case-insensitive). If a match is found,
+     * the corresponding role is returned as an Optional. If no match is found,
+     * an empty Optional is returned.</p>
      *
-     * @param name role name
-     * @return matching {@code Role}
-     * @throws IllegalArgumentException When no matching role is found
+     * @param name the name of the role to retrieve
+     * @return an Optional containing the corresponding Role if found,
+     *         or an empty Optional if no matching role exists
      */
-    public static Role fromName(String name) {
+    public static Optional<Role> fromName(String name) {
         for (Role r : values()) {
             if (r.roleName.equalsIgnoreCase(name)) {
-                return r;
+                return Optional.of(r);
             }
         }
-        throw new IllegalArgumentException("Unknown role '" + name + "'.");
+        return Optional.empty();
     }
 
     /**
-     * Returns a {@link Role} with the specified IRI or constant name.
-     * <p>
-     * This function first tries to find the enum constant by IRI. If it is not found, constant name matching is
-     * attempted.
+     * Retrieves a role based on either its IRI or role name.
      *
-     * @param identification Constant IRI or name to find match by
-     * @return matching {@code Role}
-     * @throws IllegalArgumentException When no matching role is found
+     * <p>This method first attempts to find a role using the provided identification string
+     * as an IRI. If no role is found, it then attempts to find a role using the
+     * identification string as a role name. The first successful match will be returned
+     * as an Optional. If no match is found, an empty Optional is returned.</p>
+     *
+     * @param identification the IRI or role name of the role to retrieve
+     * @return an Optional containing the corresponding Role if found,
+     *         or an empty Optional if no matching role exists
      */
-    public static Role fromIriOrName(String identification) {
-        try {
-            return fromIri(identification);
-        } catch (IllegalArgumentException e) {
-            return fromName(identification);
-        }
+    public static Optional<Role> fromIriOrName(String identification) {
+        Optional<Role> role = fromIri(identification);
+        return role.isPresent() ? role : fromName(identification);
     }
 }
diff --git a/src/main/java/cz/cvut/kbss/study/service/security/SecurityUtils.java b/src/main/java/cz/cvut/kbss/study/service/security/SecurityUtils.java
index 587e144b..05288653 100644
--- a/src/main/java/cz/cvut/kbss/study/service/security/SecurityUtils.java
+++ b/src/main/java/cz/cvut/kbss/study/service/security/SecurityUtils.java
@@ -99,10 +99,13 @@ private User resolveAccountFromOAuthPrincipal(Jwt principal) {
             throw new NotFoundException(
                     "User with username '" + userInfo.getPreferredUsername() + "' not found in repository.");
         }
-
         RoleGroup roleGroup = new RoleGroup();
         user.setRoleGroup(roleGroup);
-        roles.forEach(r ->  roleGroup.addRole(Role.fromIriOrName(r)));
+        roles.stream()
+                .map(Role::fromIriOrName)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .forEach(roleGroup::addRole);
         return user;
     }
 
diff --git a/src/test/java/cz/cvut/kbss/study/model/RoleTest.java b/src/test/java/cz/cvut/kbss/study/model/RoleTest.java
index 2346223a..46e4c901 100644
--- a/src/test/java/cz/cvut/kbss/study/model/RoleTest.java
+++ b/src/test/java/cz/cvut/kbss/study/model/RoleTest.java
@@ -8,65 +8,37 @@ class RoleTest {
 
     @Test
     void fromIriReturnsCorrectRole() {
-        assertEquals(Role.administrator, Role.fromIri(Vocabulary.s_i_RM_ADMIN));
-        assertEquals(Role.viewAllRecords, Role.fromIri(Vocabulary.s_i_view_all_records_role));
+        assertEquals(Role.administrator, Role.fromIri(Vocabulary.s_i_RM_ADMIN).get());
+        assertEquals(Role.viewAllRecords, Role.fromIri(Vocabulary.s_i_view_all_records_role).get());
     }
 
-    @Test
-    void fromIriThrowsExceptionForUnknownIri() {
-        String unknownIri = "unknown_iri";
-        Exception exception = assertThrows(IllegalArgumentException.class, () -> {
-            Role.fromIri(unknownIri);
-        });
-        assertEquals("Unknown role identifier '" + unknownIri + "'.", exception.getMessage());
-    }
-
-
     @Test
     void fromNameReturnsCorrectRole() {
-        assertEquals(Role.administrator, Role.fromName(SecurityConstants.ROLE_ADMIN));
-        assertEquals(Role.viewAllRecords, Role.fromName(SecurityConstants.viewAllRecords));
+        assertEquals(Role.administrator, Role.fromName(SecurityConstants.ROLE_ADMIN).get());
+        assertEquals(Role.viewAllRecords, Role.fromName(SecurityConstants.viewAllRecords).get());
     }
 
     @Test
     void fromNameIsCaseInsensitive() {
-        assertEquals(Role.administrator, Role.fromName(SecurityConstants.ROLE_ADMIN.toLowerCase()));
-        assertEquals(Role.viewAllRecords, Role.fromName(SecurityConstants.viewAllRecords.toUpperCase()));
-    }
-
-    @Test
-    void fromNameThrowsExceptionForUnknownName() {
-        String unknownName = "unknown_role";
-        Exception exception = assertThrows(IllegalArgumentException.class, () -> {
-            Role.fromName(unknownName);
-        });
-        assertEquals("Unknown role '" + unknownName + "'.", exception.getMessage());
+        assertEquals(Role.administrator, Role.fromName(SecurityConstants.ROLE_ADMIN.toLowerCase()).get());
+        assertEquals(Role.viewAllRecords, Role.fromName(SecurityConstants.viewAllRecords.toUpperCase()).get());
     }
 
-
     @Test
     void fromIriOrNameReturnsRoleByIri() {
-        assertEquals(Role.administrator, Role.fromIriOrName(Vocabulary.s_i_RM_ADMIN));
-        assertEquals(Role.viewAllRecords, Role.fromIriOrName(Vocabulary.s_i_view_all_records_role));
+        assertEquals(Role.administrator, Role.fromIriOrName(Vocabulary.s_i_RM_ADMIN).get());
+        assertEquals(Role.viewAllRecords, Role.fromIriOrName(Vocabulary.s_i_view_all_records_role).get());
     }
 
     @Test
     void fromIriOrNameReturnsRoleByName() {
-        assertEquals(Role.administrator, Role.fromIriOrName(SecurityConstants.ROLE_ADMIN));
-        assertEquals(Role.viewAllRecords, Role.fromIriOrName(SecurityConstants.viewAllRecords));
+        assertEquals(Role.administrator, Role.fromIriOrName(SecurityConstants.ROLE_ADMIN).get());
+        assertEquals(Role.viewAllRecords, Role.fromIriOrName(SecurityConstants.viewAllRecords).get());
     }
 
     @Test
     void fromIriOrNameIsCaseInsensitiveForName() {
-        assertEquals(Role.administrator, Role.fromIriOrName(SecurityConstants.ROLE_ADMIN.toLowerCase()));
+        assertEquals(Role.administrator, Role.fromIriOrName(SecurityConstants.ROLE_ADMIN.toLowerCase()).get());
     }
 
-    @Test
-    void fromIriOrNameThrowsExceptionForUnknownIdentifier() {
-        String unknownIdentifier = "unknown_identifier";
-        Exception exception = assertThrows(IllegalArgumentException.class, () -> {
-            Role.fromIriOrName(unknownIdentifier);
-        });
-        assertEquals("Unknown role '" + unknownIdentifier + "'.", exception.getMessage());
-    }
 }