We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
Internal Error with setup
Hi,

Thanks for the work !

I want to try the new version with setup.mailu.io + Docker stack. However I have already this when I want to generate my compose:

> Internal Server Error
> The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.

Is it normal?

--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `setup/server.py`
Content:
```
1 import flask
2 import flask_bootstrap
3 import redis
4 import json
5 import os
6 import jinja2
7 import uuid
8 import string
9 import random
10 import ipaddress
11 import hashlib
12 import time
13 
14 
15 version = os.getenv("this_version", "master")
16 static_url_path = "/" + version + "/static"
17 app = flask.Flask(__name__, static_url_path=static_url_path)
18 flask_bootstrap.Bootstrap(app)
19 db = redis.StrictRedis(host='redis', port=6379, db=0)
20 
21 
22 def render_flavor(flavor, template, data):
23     return flask.render_template(
24         os.path.join(flavor, template),
25         **data
26     )
27 
28 
29 @app.add_template_global
30 def secret(length=16):
31     charset = string.ascii_uppercase + string.digits
32     return ''.join(
33         random.SystemRandom().choice(charset)
34         for _ in range(length)
35     )
36 
37 #Original copied from https://github.com/andrewlkho/ulagen
38 def random_ipv6_subnet():
39     eui64 = uuid.getnode() >> 24 << 48 | 0xfffe000000 | uuid.getnode() & 0xffffff
40     eui64_canon = "-".join([format(eui64, "02X")[i:i+2] for i in range(0, 18, 2)])
41 
42     h = hashlib.sha1()
43     h.update((eui64_canon + str(time.time() - time.mktime((1900, 1, 1, 0, 0, 0, 0, 1, -1)))).encode('utf-8'))
44     globalid = h.hexdigest()[0:10]
45 
46     prefix = ":".join(("fd" + globalid[0:2], globalid[2:6], globalid[6:10]))
47     return prefix
48 
49 def build_app(path):
50 
51     app.jinja_env.trim_blocks = True
52     app.jinja_env.lstrip_blocks = True
53 
54     @app.context_processor
55     def app_context():
56         return dict(versions=os.getenv("VERSIONS","master").split(','))
57 
58     prefix_bp = flask.Blueprint(version, __name__)
59     prefix_bp.jinja_loader = jinja2.ChoiceLoader([
60         jinja2.FileSystemLoader(os.path.join(path, "templates")),
61         jinja2.FileSystemLoader(os.path.join(path, "flavors"))
62     ])
63 
64     root_bp = flask.Blueprint("root", __name__)
65     root_bp.jinja_loader = jinja2.ChoiceLoader([
66         jinja2.FileSystemLoader(os.path.join(path, "templates")),
67         jinja2.FileSystemLoader(os.path.join(path, "flavors"))
68     ])
69 
70     @prefix_bp.context_processor
71     @root_bp.context_processor
72     def bp_context(version=version):
73         return dict(version=version)
74 
75     @prefix_bp.route("/")
76     @root_bp.route("/")
77     def wizard():
78         return flask.render_template('wizard.html')
79 
80     @prefix_bp.route("/submit_flavor", methods=["POST"])
81     @root_bp.route("/submit_flavor", methods=["POST"])
82     def submit_flavor():
83         data = flask.request.form.copy()
84         subnet6 = random_ipv6_subnet()
85         steps = sorted(os.listdir(os.path.join(path, "templates", "steps", data["flavor"])))
86         return flask.render_template('wizard.html', flavor=data["flavor"], steps=steps, subnet6=subnet6)
87 
88     @prefix_bp.route("/submit", methods=["POST"])
89     @root_bp.route("/submit", methods=["POST"])
90     def submit():
91         data = flask.request.form.copy()
92         data['uid'] = str(uuid.uuid4())
93         data['dns'] = str(ipaddress.IPv4Network(data['subnet'])[-2])
94         db.set(data['uid'], json.dumps(data))
95         return flask.redirect(flask.url_for('.setup', uid=data['uid']))
96 
97     @prefix_bp.route("/setup/<uid>", methods=["GET"])
98     @root_bp.route("/setup/<uid>", methods=["GET"])
99     def setup(uid):
100         data = json.loads(db.get(uid))
101         flavor = data.get("flavor", "compose")
102         rendered = render_flavor(flavor, "setup.html", data)
103         return flask.render_template("setup.html", contents=rendered)
104 
105     @prefix_bp.route("/file/<uid>/<filepath>", methods=["GET"])
106     @root_bp.route("/file/<uid>/<filepath>", methods=["GET"])
107     def file(uid, filepath):
108         data = json.loads(db.get(uid))
109         flavor = data.get("flavor", "compose")
110         return flask.Response(
111             render_flavor(flavor, filepath, data),
112             mimetype="application/text"
113         )
114 
115     app.register_blueprint(prefix_bp, url_prefix="/{}".format(version))
116     app.register_blueprint(root_bp)
117 
118 
119 if __name__ == "__main__":
120     build_app("/tmp/mailutest")
121     app.run(debug=True)
122
```
--- END FILES ---

Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.

Here is an example:

```diff
diff --git a/examples/server_async.py b/examples/server_async.py
--- a/examples/server_async.py
+++ b/examples/server_async.py
@@ -313,4 +313,4 @@
 
 
 if __name__ == "__main__":
-    asyncio.run(run_async_server("."), debug=True)
+    asyncio.run(run_async_server(), debug=True)
diff --git a/examples/server_sync.py b/examples/server_sync.py
--- a/examples/server_sync.py
+++ b/examples/server_sync.py
@@ -313,5 +313,5 @@
 
 
 if __name__ == "__main__":
-    server = run_sync_server(".")
+    server = run_sync_server()
     server.shutdown()

```

diff --git a/setup/server.py b/setup/server.py
--- a/setup/server.py
+++ b/setup/server.py
@@ -90,7 +90,10 @@
     def submit():
         data = flask.request.form.copy()
         data['uid'] = str(uuid.uuid4())
-        data['dns'] = str(ipaddress.IPv4Network(data['subnet'])[-2])
+        try:
+            data['dns'] = str(ipaddress.IPv4Network(data['subnet'])[-2])
+        except ValueError as err:
+            return "Error while generating files: " + str(err)
         db.set(data['uid'], json.dumps(data))
         return flask.redirect(flask.url_for('.setup', uid=data['uid']))

{"golden_diff": "diff --git a/setup/server.py b/setup/server.py\n--- a/setup/server.py\n+++ b/setup/server.py\n@@ -90,7 +90,10 @@\n     def submit():\n         data = flask.request.form.copy()\n         data['uid'] = str(uuid.uuid4())\n-        data['dns'] = str(ipaddress.IPv4Network(data['subnet'])[-2])\n+        try:\n+            data['dns'] = str(ipaddress.IPv4Network(data['subnet'])[-2])\n+        except ValueError as err:\n+            return \"Error while generating files: \" + str(err)\n         db.set(data['uid'], json.dumps(data))\n         return flask.redirect(flask.url_for('.setup', uid=data['uid']))\n", "issue": "Internal Error with setup\nHi,\r\n\r\nThanks for the work !\r\n\r\nI want to try the new version with setup.mailu.io + Docker stack. However I have already this when I want to generate my compose:\r\n\r\n> Internal Server Error\r\n> The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.\r\n\r\nIs it normal?\n", "before_files": [{"content": "import flask\nimport flask_bootstrap\nimport redis\nimport json\nimport os\nimport jinja2\nimport uuid\nimport string\nimport random\nimport ipaddress\nimport hashlib\nimport time\n\n\nversion = os.getenv(\"this_version\", \"master\")\nstatic_url_path = \"/\" + version + \"/static\"\napp = flask.Flask(__name__, static_url_path=static_url_path)\nflask_bootstrap.Bootstrap(app)\ndb = redis.StrictRedis(host='redis', port=6379, db=0)\n\n\ndef render_flavor(flavor, template, data):\n    return flask.render_template(\n        os.path.join(flavor, template),\n        **data\n    )\n\n\n@app.add_template_global\ndef secret(length=16):\n    charset = string.ascii_uppercase + string.digits\n    return ''.join(\n        random.SystemRandom().choice(charset)\n        for _ in range(length)\n    )\n\n#Original copied from https://github.com/andrewlkho/ulagen\ndef random_ipv6_subnet():\n    eui64 = uuid.getnode() >> 24 << 48 | 0xfffe000000 | uuid.getnode() & 0xffffff\n    eui64_canon = \"-\".join([format(eui64, \"02X\")[i:i+2] for i in range(0, 18, 2)])\n\n    h = hashlib.sha1()\n    h.update((eui64_canon + str(time.time() - time.mktime((1900, 1, 1, 0, 0, 0, 0, 1, -1)))).encode('utf-8'))\n    globalid = h.hexdigest()[0:10]\n\n    prefix = \":\".join((\"fd\" + globalid[0:2], globalid[2:6], globalid[6:10]))\n    return prefix\n\ndef build_app(path):\n\n    app.jinja_env.trim_blocks = True\n    app.jinja_env.lstrip_blocks = True\n\n    @app.context_processor\n    def app_context():\n        return dict(versions=os.getenv(\"VERSIONS\",\"master\").split(','))\n\n    prefix_bp = flask.Blueprint(version, __name__)\n    prefix_bp.jinja_loader = jinja2.ChoiceLoader([\n        jinja2.FileSystemLoader(os.path.join(path, \"templates\")),\n        jinja2.FileSystemLoader(os.path.join(path, \"flavors\"))\n    ])\n\n    root_bp = flask.Blueprint(\"root\", __name__)\n    root_bp.jinja_loader = jinja2.ChoiceLoader([\n        jinja2.FileSystemLoader(os.path.join(path, \"templates\")),\n        jinja2.FileSystemLoader(os.path.join(path, \"flavors\"))\n    ])\n\n    @prefix_bp.context_processor\n    @root_bp.context_processor\n    def bp_context(version=version):\n        return dict(version=version)\n\n    @prefix_bp.route(\"/\")\n    @root_bp.route(\"/\")\n    def wizard():\n        return flask.render_template('wizard.html')\n\n    @prefix_bp.route(\"/submit_flavor\", methods=[\"POST\"])\n    @root_bp.route(\"/submit_flavor\", methods=[\"POST\"])\n    def submit_flavor():\n        data = flask.request.form.copy()\n        subnet6 = random_ipv6_subnet()\n        steps = sorted(os.listdir(os.path.join(path, \"templates\", \"steps\", data[\"flavor\"])))\n        return flask.render_template('wizard.html', flavor=data[\"flavor\"], steps=steps, subnet6=subnet6)\n\n    @prefix_bp.route(\"/submit\", methods=[\"POST\"])\n    @root_bp.route(\"/submit\", methods=[\"POST\"])\n    def submit():\n        data = flask.request.form.copy()\n        data['uid'] = str(uuid.uuid4())\n        data['dns'] = str(ipaddress.IPv4Network(data['subnet'])[-2])\n        db.set(data['uid'], json.dumps(data))\n        return flask.redirect(flask.url_for('.setup', uid=data['uid']))\n\n    @prefix_bp.route(\"/setup/<uid>\", methods=[\"GET\"])\n    @root_bp.route(\"/setup/<uid>\", methods=[\"GET\"])\n    def setup(uid):\n        data = json.loads(db.get(uid))\n        flavor = data.get(\"flavor\", \"compose\")\n        rendered = render_flavor(flavor, \"setup.html\", data)\n        return flask.render_template(\"setup.html\", contents=rendered)\n\n    @prefix_bp.route(\"/file/<uid>/<filepath>\", methods=[\"GET\"])\n    @root_bp.route(\"/file/<uid>/<filepath>\", methods=[\"GET\"])\n    def file(uid, filepath):\n        data = json.loads(db.get(uid))\n        flavor = data.get(\"flavor\", \"compose\")\n        return flask.Response(\n            render_flavor(flavor, filepath, data),\n            mimetype=\"application/text\"\n        )\n\n    app.register_blueprint(prefix_bp, url_prefix=\"/{}\".format(version))\n    app.register_blueprint(root_bp)\n\n\nif __name__ == \"__main__\":\n    build_app(\"/tmp/mailutest\")\n    app.run(debug=True)\n", "path": "setup/server.py"}], "after_files": [{"content": "import flask\nimport flask_bootstrap\nimport redis\nimport json\nimport os\nimport jinja2\nimport uuid\nimport string\nimport random\nimport ipaddress\nimport hashlib\nimport time\n\n\nversion = os.getenv(\"this_version\", \"master\")\nstatic_url_path = \"/\" + version + \"/static\"\napp = flask.Flask(__name__, static_url_path=static_url_path)\nflask_bootstrap.Bootstrap(app)\ndb = redis.StrictRedis(host='redis', port=6379, db=0)\n\n\ndef render_flavor(flavor, template, data):\n    return flask.render_template(\n        os.path.join(flavor, template),\n        **data\n    )\n\n\n@app.add_template_global\ndef secret(length=16):\n    charset = string.ascii_uppercase + string.digits\n    return ''.join(\n        random.SystemRandom().choice(charset)\n        for _ in range(length)\n    )\n\n#Original copied from https://github.com/andrewlkho/ulagen\ndef random_ipv6_subnet():\n    eui64 = uuid.getnode() >> 24 << 48 | 0xfffe000000 | uuid.getnode() & 0xffffff\n    eui64_canon = \"-\".join([format(eui64, \"02X\")[i:i+2] for i in range(0, 18, 2)])\n\n    h = hashlib.sha1()\n    h.update((eui64_canon + str(time.time() - time.mktime((1900, 1, 1, 0, 0, 0, 0, 1, -1)))).encode('utf-8'))\n    globalid = h.hexdigest()[0:10]\n\n    prefix = \":\".join((\"fd\" + globalid[0:2], globalid[2:6], globalid[6:10]))\n    return prefix\n\ndef build_app(path):\n\n    app.jinja_env.trim_blocks = True\n    app.jinja_env.lstrip_blocks = True\n\n    @app.context_processor\n    def app_context():\n        return dict(versions=os.getenv(\"VERSIONS\",\"master\").split(','))\n\n    prefix_bp = flask.Blueprint(version, __name__)\n    prefix_bp.jinja_loader = jinja2.ChoiceLoader([\n        jinja2.FileSystemLoader(os.path.join(path, \"templates\")),\n        jinja2.FileSystemLoader(os.path.join(path, \"flavors\"))\n    ])\n\n    root_bp = flask.Blueprint(\"root\", __name__)\n    root_bp.jinja_loader = jinja2.ChoiceLoader([\n        jinja2.FileSystemLoader(os.path.join(path, \"templates\")),\n        jinja2.FileSystemLoader(os.path.join(path, \"flavors\"))\n    ])\n\n    @prefix_bp.context_processor\n    @root_bp.context_processor\n    def bp_context(version=version):\n        return dict(version=version)\n\n    @prefix_bp.route(\"/\")\n    @root_bp.route(\"/\")\n    def wizard():\n        return flask.render_template('wizard.html')\n\n    @prefix_bp.route(\"/submit_flavor\", methods=[\"POST\"])\n    @root_bp.route(\"/submit_flavor\", methods=[\"POST\"])\n    def submit_flavor():\n        data = flask.request.form.copy()\n        subnet6 = random_ipv6_subnet()\n        steps = sorted(os.listdir(os.path.join(path, \"templates\", \"steps\", data[\"flavor\"])))\n        return flask.render_template('wizard.html', flavor=data[\"flavor\"], steps=steps, subnet6=subnet6)\n\n    @prefix_bp.route(\"/submit\", methods=[\"POST\"])\n    @root_bp.route(\"/submit\", methods=[\"POST\"])\n    def submit():\n        data = flask.request.form.copy()\n        data['uid'] = str(uuid.uuid4())\n        try:\n            data['dns'] = str(ipaddress.IPv4Network(data['subnet'])[-2])\n        except ValueError as err:\n            return \"Error while generating files: \" + str(err)\n        db.set(data['uid'], json.dumps(data))\n        return flask.redirect(flask.url_for('.setup', uid=data['uid']))\n\n    @prefix_bp.route(\"/setup/<uid>\", methods=[\"GET\"])\n    @root_bp.route(\"/setup/<uid>\", methods=[\"GET\"])\n    def setup(uid):\n        data = json.loads(db.get(uid))\n        flavor = data.get(\"flavor\", \"compose\")\n        rendered = render_flavor(flavor, \"setup.html\", data)\n        return flask.render_template(\"setup.html\", contents=rendered)\n\n    @prefix_bp.route(\"/file/<uid>/<filepath>\", methods=[\"GET\"])\n    @root_bp.route(\"/file/<uid>/<filepath>\", methods=[\"GET\"])\n    def file(uid, filepath):\n        data = json.loads(db.get(uid))\n        flavor = data.get(\"flavor\", \"compose\")\n        return flask.Response(\n            render_flavor(flavor, filepath, data),\n            mimetype=\"application/text\"\n        )\n\n    app.register_blueprint(prefix_bp, url_prefix=\"/{}\".format(version))\n    app.register_blueprint(root_bp)\n\n\nif __name__ == \"__main__\":\n    build_app(\"/tmp/mailutest\")\n    app.run(debug=True)\n", "path": "setup/server.py"}]}