diff --git a/CHANGELOG.md b/CHANGELOG.md
index 30bd12d0..076ef587 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -30,6 +30,7 @@ The **patch** part changes incrementally at each release.
 * apt: disable APT Periodic
 * evoacme: upstream release 20.12
 * evocheck: upstream release 20.12
+* tomcat-instance: fail if uid already exists
 
 ### Fixed
 
diff --git a/tomcat-instance/tasks/user.yml b/tomcat-instance/tasks/user.yml
index a4a7bcb2..64244799 100644
--- a/tomcat-instance/tasks/user.yml
+++ b/tomcat-instance/tasks/user.yml
@@ -1,4 +1,24 @@
 ---
+
+- fail:
+    msg: "You must provide a value for the 'tomcat_instance_port' variable."
+  when: tomcat_instance_port is not defined or tomcat_instance_port == ''
+
+
+- name: "Test if uid '{{ tomcat_instance_port }}' exists"
+  command: 'id -un -- "{{ tomcat_instance_port }}"'
+  register: get_login_from_id
+  failed_when: False
+  changed_when: False
+  check_mode: no
+
+- name: "Fail if uid already exists for another user"
+  fail:
+    msg: "Uid '{{ tomcat_instance_port }}' is already used by '{{ get_login_from_id.stdout }}'. You must change uid for '{{ tomcat_instance_name }}'"
+  when:
+    - get_login_from_id.rc == 0
+    - get_login_from_id.stdout != tomcat_instance_name
+
 - name: Create group instance
   group:
     name: "{{ tomcat_instance_name }}"