Периодически вываливается Error 500 в Flask

#!/usr/bin/env python3
 
from db import session
from grabber import Job
 
from flask import Flask, request, Response
from werkzeug.contrib.fixers import ProxyFix
 
import PyRSS2Gen
import datetime
import logging
 
from sqlalchemy import desc, or_
 
import config
 
 
app = Flask(__name__)
app.debug = config.debug
app.wsgi_app = ProxyFix(app.wsgi_app)
 
 
@app.route('/rss')
def rss():
    new_feed_items = []
 
    # Filters
    filters = []
 
    keywords_filters = []
    keywords = config.post_filters.get('keywords', None)
    if keywords:
        for keyword in keywords:
            keywords_filters.append(Job.title.ilike('%' + keyword.lower() + '%'))
            keywords_filters.append(Job.description.ilike('%' + keyword.lower() + '%'))
    filters.append(or_(*keywords_filters))
 
    jobs = session.query(Job).filter(*filters).order_by(desc(Job.published)).limit(config.items_in_feed).all()
    for job in jobs:
        new_feed_items.append(PyRSS2Gen.RSSItem(
            title = job.title,
            link = job.url,
            description = job.description,
            guid = job.url,
            pubDate = job.published
        ))
 
    # Формируем новую RSS ленту
    new_feed = PyRSS2Gen.RSS2(
        title = 'Freelance jobs',
        link = '',
        description = '',
        generator = 'Freelance Grabber',
        items = new_feed_items
    )
 
    return Response(new_feed.to_xml("utf-8"), mimetype='text/xml')
 
 
 
if __name__ == '__main__':
    app.run()