diff --git a/lib/job_server.py b/lib/job_server.py
index 0641740..dc06096 100755
--- a/lib/job_server.py
+++ b/lib/job_server.py
@@ -14,7 +14,7 @@ from flask import Flask, request, render_template, send_file, after_this_request
 from werkzeug.utils import secure_filename
 
 from lib.render_job import RenderJob
-from lib.render_queue import RenderQueue
+from lib.render_queue import RenderQueue, JobNotFoundError
 from lib.server_helper import post_job_to_server, generate_thumbnail_for_job
 from utilities.render_worker import RenderWorkerFactory, string_to_status, RenderStatus
 
@@ -53,22 +53,20 @@ def index():
 @server.route('/ui/job/<job_id>/full_details')
 def job_detail(job_id):
     found_job = RenderQueue.job_with_id(job_id)
-    if found_job:
-        table_html = json2html.json2html.convert(json=found_job.json(),
-                                                 table_attributes='class="table is-narrow is-striped is-fullwidth"')
-        media_url = None
-        if found_job.file_list() and found_job.render_status() == RenderStatus.COMPLETED:
-            media_basename = os.path.basename(found_job.file_list()[0])
-            media_url = f"/api/job/{job_id}/file/{media_basename}"
-        return render_template('details.html', detail_table=table_html, media_url=media_url,
-                               hostname=RenderQueue.host_name, job_status=found_job.render_status().value.title(),
-                               job=found_job, renderer_info=renderer_info())
-    return f'Cannot find job with ID {job_id}', 400
+    table_html = json2html.json2html.convert(json=found_job.json(),
+                                             table_attributes='class="table is-narrow is-striped is-fullwidth"')
+    media_url = None
+    if found_job.file_list() and found_job.render_status() == RenderStatus.COMPLETED:
+        media_basename = os.path.basename(found_job.file_list()[0])
+        media_url = f"/api/job/{job_id}/file/{media_basename}"
+    return render_template('details.html', detail_table=table_html, media_url=media_url,
+                           hostname=RenderQueue.host_name, job_status=found_job.render_status().value.title(),
+                           job=found_job, renderer_info=renderer_info())
 
 
 @server.route('/ui/job/<job_id>/thumbnail')
 def job_thumbnail(job_id):
-    found_job = RenderQueue.job_with_id(job_id)
+    found_job = RenderQueue.job_with_id(job_id, none_ok=True)
     if found_job:
 
         os.makedirs(server.config['THUMBS_FOLDER'], exist_ok=True)
@@ -112,27 +110,25 @@ def filtered_jobs_json(status_val):
         return f'Cannot find jobs with status {status_val}', 400
 
 
+@server.errorhandler(JobNotFoundError)
+def handle_job_not_found(job_error):
+    return f'Cannot find job with ID {job_error.job_id}', 400
+
+
 @server.get('/api/job/<job_id>')
 def get_job_status(job_id):
-    found_job = RenderQueue.job_with_id(job_id)
-    if found_job:
-        return found_job.json()
-    else:
-        return f'Cannot find job with ID {job_id}', 400
+    return RenderQueue.job_with_id(job_id).json()
 
 
 @server.get('/api/job/<job_id>/logs')
 def get_job_logs(job_id):
     found_job = RenderQueue.job_with_id(job_id)
-    if found_job:
-        log_path = found_job.worker.log_path
-        log_data = None
-        if log_path and os.path.exists(log_path):
-            with open(log_path) as file:
-                log_data = file.read()
-        return Response(log_data, mimetype='text/plain')
-    else:
-        return f'Cannot find job with ID {job_id}', 400
+    log_path = found_job.worker.log_path
+    log_data = None
+    if log_path and os.path.exists(log_path):
+        with open(log_path) as file:
+            log_data = file.read()
+    return Response(log_data, mimetype='text/plain')
 
 
 @server.get('/api/job/<job_id>/file_list')
@@ -155,19 +151,16 @@ def download_all(job_id):
         return response
 
     found_job = RenderQueue.job_with_id(job_id)
-    if found_job:
-        output_dir = os.path.dirname(found_job.worker.output_path)
-        if os.path.exists(output_dir):
-            zip_filename = os.path.join('/tmp', pathlib.Path(found_job.worker.input_path).stem + '.zip')
-            with ZipFile(zip_filename, 'w') as zipObj:
-                for f in os.listdir(output_dir):
-                    zipObj.write(filename=os.path.join(output_dir, f),
-                                 arcname=os.path.basename(f))
-            return send_file(zip_filename, mimetype="zip", as_attachment=True, )
-        else:
-            return f'Cannot find project files for job {job_id}', 500
+    output_dir = os.path.dirname(found_job.worker.output_path)
+    if os.path.exists(output_dir):
+        zip_filename = os.path.join('/tmp', pathlib.Path(found_job.worker.input_path).stem + '.zip')
+        with ZipFile(zip_filename, 'w') as zipObj:
+            for f in os.listdir(output_dir):
+                zipObj.write(filename=os.path.join(output_dir, f),
+                             arcname=os.path.basename(f))
+        return send_file(zip_filename, mimetype="zip", as_attachment=True, )
     else:
-        return f'Cannot find job with ID {job_id}', 400
+        return f'Cannot find project files for job {job_id}', 500
 
 
 @server.post('/api/register_client')
@@ -364,13 +357,10 @@ def add_job(job_params, remove_job_dir_on_failure=False):
 
 @server.get('/api/job/<job_id>/cancel')
 def cancel_job(job_id):
-    found_job = RenderQueue.job_with_id(job_id)
-    if not found_job:
-        return f'Cannot find job with ID {job_id}', 400
-    elif not request.args.get('confirm', False):
+    if not request.args.get('confirm', False):
         return 'Confirmation required to cancel job', 400
 
-    if RenderQueue.cancel_job(found_job):
+    if RenderQueue.cancel_job(RenderQueue.job_with_id(job_id)):
         if request.args.get('redirect', False):
             return redirect(url_for('index'))
         else:
@@ -382,13 +372,11 @@ def cancel_job(job_id):
 @server.route('/api/job/<job_id>/delete', methods=['POST', 'GET'])
 def delete_job(job_id):
     try:
-        found_job = RenderQueue.job_with_id(job_id)
-        if not found_job:
-            return f'Cannot find job with ID {job_id}', 400
-        elif not request.args.get('confirm', False):
+        if not request.args.get('confirm', False):
             return 'Confirmation required to delete job', 400
 
         # First, remove all render files and logs
+        found_job = RenderQueue.job_with_id(job_id)
         files_to_delete = found_job.file_list()
         files_to_delete.append(found_job.log_path())
         for d in files_to_delete:
diff --git a/lib/render_queue.py b/lib/render_queue.py
index e351e19..9fbe061 100755
--- a/lib/render_queue.py
+++ b/lib/render_queue.py
@@ -16,6 +16,12 @@ JSON_FILE = 'server_state.json'
 #todo: move history to sqlite db
 
 
+class JobNotFoundError(Exception):
+    def __init__(self, job_id, *args):
+        super().__init__(args)
+        self.job_id = job_id
+
+
 class RenderQueue:
     job_queue = []
     render_clients = []
@@ -61,8 +67,10 @@ class RenderQueue:
         return found_jobs
 
     @classmethod
-    def job_with_id(cls, job_id):
+    def job_with_id(cls, job_id, none_ok=False):
         found_job = next((x for x in cls.job_queue if x.id == job_id), None)
+        if not found_job and not none_ok:
+            raise JobNotFoundError(job_id)
         return found_job
 
     @classmethod