diff --git a/CHANGELOG.md b/CHANGELOG.md
index b72c937..4407fe1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,21 @@
 # Matemat Changelog
 
+<!-- BEGIN RELEASE v0.3.15 -->
+## Version 0.3.15
+
+Websocket-based EAN code handling
+
+### Changes
+
+<!-- BEGIN CHANGES 0.3.15 -->
+- breaking: remove the config option to automatically close tabs after ean purchase
+- fix: improve error handling on database consistency errors (e.g. non-unique ean codes) in the settings
+- feat: handle ean codes in the already open tab via a websocket connection
+- feat: populate ean code input field when a barcode is scanned while in the product settings
+<!-- END CHANGES 0.3.15 -->
+
+<!-- END RELEASE v0.3.15 -->
+
 <!-- BEGIN RELEASE v0.3.14 -->
 ## Version 0.3.14
 
diff --git a/matemat/__init__.py b/matemat/__init__.py
index d9195dc..67cbcd2 100644
--- a/matemat/__init__.py
+++ b/matemat/__init__.py
@@ -1,2 +1,2 @@
 
-__version__ = '0.3.14'
+__version__ = '0.3.15'
diff --git a/matemat/exceptions/DatabaseConsistencyError.py b/matemat/exceptions/DatabaseConsistencyError.py
index 5f91b58..89818f1 100644
--- a/matemat/exceptions/DatabaseConsistencyError.py
+++ b/matemat/exceptions/DatabaseConsistencyError.py
@@ -2,7 +2,7 @@
 from typing import Optional
 
 
-class DatabaseConsistencyError(BaseException):
+class DatabaseConsistencyError(Exception):
 
     def __init__(self, msg: Optional[str] = None) -> None:
         self._msg: Optional[str] = msg
diff --git a/matemat/webserver/pagelets/admin.py b/matemat/webserver/pagelets/admin.py
index 9018f25..99f3771 100644
--- a/matemat/webserver/pagelets/admin.py
+++ b/matemat/webserver/pagelets/admin.py
@@ -13,6 +13,7 @@ from matemat.exceptions import AuthenticationError, DatabaseConsistencyError
 from matemat.util.currency_format import parse_chf
 from matemat.webserver import session, template
 from matemat.webserver.config import get_app_config, get_stock_provider
+from matemat.webserver.template import Notification
 
 
 @get('/admin')
@@ -207,7 +208,7 @@ def handle_admin_change(args: FormsDict, files: FormsDict, db: MatematDatabase):
             custom_price = 'custom_price' in args
             stockable = 'stockable' in args
             ean = str(args.ean) or None
-            # Create the user in the database
+            # Create the product in the database
             newproduct = db.create_product(name, price_member, price_non_member, custom_price, stockable, ean)
             # If a new product image was uploaded, process it
             image = files.image.file.read() if 'image' in files else None
@@ -226,7 +227,8 @@ def handle_admin_change(args: FormsDict, files: FormsDict, db: MatematDatabase):
                     image.thumbnail((150, 150), Image.LANCZOS)
                     # Write the image to the file
                     image.save(os.path.join(abspath, f'{newproduct.id}.png'), 'PNG')
-                except OSError:
+                except OSError as e:
+                    Notification.error(str(e), decay=True)
                     return
             else:
                 # If no image was uploaded and a default avatar is set, copy it to the product's avatar path
@@ -282,8 +284,10 @@ def handle_admin_change(args: FormsDict, files: FormsDict, db: MatematDatabase):
                     image.thumbnail((150, 150), Image.LANCZOS)
                     # Write the image to the file
                     image.save(os.path.join(abspath, f'default.png'), 'PNG')
-                except OSError:
+                except OSError as e:
+                    Notification.error(str(e), decay=True)
                     return
 
-    except UnicodeDecodeError:
-        raise ValueError('an argument not a string')
+    except Exception as e:
+        Notification.error(str(e), decay=True)
+        return
diff --git a/matemat/webserver/pagelets/buy.py b/matemat/webserver/pagelets/buy.py
index 96296b4..84b7855 100644
--- a/matemat/webserver/pagelets/buy.py
+++ b/matemat/webserver/pagelets/buy.py
@@ -26,7 +26,6 @@ def buy():
         if 'pid' in request.params:
             pid = int(str(request.params.pid))
             product = db.get_product(pid)
-            closetab = int(str(request.params.closetab) or 0)
             if c.get_dispenser().dispense(product, 1):
                 price = product.price_member if user.is_member else product.price_non_member
                 if 'price' in request.params:
@@ -38,7 +37,7 @@ def buy():
                     stock_provider.update_stock(product, -1)
                 # Logout user if configured, logged in via touchkey and no price entry input was shown
                 if user.logout_after_purchase and authlevel < 2 and not product.custom_price:
-                    redirect(f'/logout?lastaction=buy&lastproduct={pid}&lastprice={price}&closetab={closetab}')
+                    redirect(f'/logout?lastaction=buy&lastproduct={pid}&lastprice={price}')
                 # Redirect to the main page (where this request should have come from)
-                redirect(f'/?lastaction=buy&lastproduct={pid}&lastprice={price}&closetab={closetab}')
+                redirect(f'/?lastaction=buy&lastproduct={pid}&lastprice={price}')
     redirect('/')
diff --git a/matemat/webserver/pagelets/main.py b/matemat/webserver/pagelets/main.py
index 6cf7c65..7f9a255 100644
--- a/matemat/webserver/pagelets/main.py
+++ b/matemat/webserver/pagelets/main.py
@@ -20,7 +20,6 @@ def main_page():
     with MatematDatabase(config['DatabaseFile']) as db:
         # Fetch the list of products to display
         products = db.list_products()
-        closetab = int(str(request.params.closetab) or 0)
         lastprice = int(request.params.lastprice) if request.params.lastprice else None
         if request.params.lastaction == 'deposit' and lastprice:
             Notification.success(f'Deposited {format_chf(lastprice)}', decay=True)
@@ -28,6 +27,7 @@ def main_page():
             lastproduct = db.get_product(request.params.lastproduct)
             Notification.success(f'Purchased {lastproduct.name} for {format_chf(lastprice)}', decay=True)
         buyproduct = None
+
         if request.params.ean:
             try:
                 buyproduct = db.get_product_by_ean(request.params.ean)
@@ -35,6 +35,7 @@ def main_page():
                     f'Login will purchase <strong>{buyproduct.name}</strong>. Click <a href="/">here</a> to abort.')
             except ValueError:
                 Notification.error(f'EAN code {request.params.ean} is not associated with any product.', decay=True)
+
         # Check whether a user is logged in
         if session.has(session_id, 'authenticated_user'):
             # Fetch the user id and authentication level (touchkey vs password) from the session storage
@@ -42,10 +43,7 @@ def main_page():
             authlevel: int = session.get(session_id, 'authentication_level')
             # If an EAN code was scanned, directly trigger the purchase
             if buyproduct:
-                url = f'/buy?pid={buyproduct.id}'
-                if config.get('CloseTabAfterEANPurchase', '0') == '1':
-                    url += '&closetab=1'
-                redirect(url)
+                redirect(f'/buy?pid={buyproduct.id}')
             # Fetch the user object from the database (for name display, price calculation and admin check)
             users = db.list_users()
             user = db.get_user(uid)
@@ -62,4 +60,4 @@ def main_page():
             return template.render('userlist.html',
                                    users=users, setupname=config['InstanceName'], now=now,
                                    signup=(config.get('SignupEnabled', '0') == '1'),
-                                   buyproduct=buyproduct, closetab=closetab)
+                                   buyproduct=buyproduct)
diff --git a/matemat/webserver/pagelets/touchkey.py b/matemat/webserver/pagelets/touchkey.py
index 3494940..9395431 100644
--- a/matemat/webserver/pagelets/touchkey.py
+++ b/matemat/webserver/pagelets/touchkey.py
@@ -51,10 +51,7 @@ def touchkey_page():
             session.put(session_id, 'authentication_level', 1)
             if request.params.buypid:
                 buypid = str(request.params.buypid)
-                url = f'/buy?pid={buypid}'
-                if config.get('CloseTabAfterEANPurchase', '0') == '1':
-                    url += '&closetab=1'
-                redirect(url)
+                redirect(f'/buy?pid={buypid}')
             # Redirect to the main page, showing the product list
             redirect('/')
         # If neither GET nor POST was used, show a 405 Method Not Allowed error page
diff --git a/matemat/webserver/template/template.py b/matemat/webserver/template/template.py
index e3b04ad..f048af6 100644
--- a/matemat/webserver/template/template.py
+++ b/matemat/webserver/template/template.py
@@ -2,10 +2,15 @@ from typing import Any, Dict
 
 import os.path
 import jinja2
+import netaddr
+
+from bottle import request
 
 from matemat import __version__
 from matemat.util.currency_format import format_chf
 from matemat.webserver.template import Notification
+from matemat.webserver.config import get_app_config
+
 
 __jinja_env: jinja2.Environment = None
 
@@ -22,9 +27,16 @@ def init(config: Dict[str, Any]) -> None:
 
 def render(name: str, **kwargs):
     global __jinja_env
+    config = get_app_config()
     template: jinja2.Template = __jinja_env.get_template(name)
+    wsacl = netaddr.IPSet([addr.strip() for addr in config.get('EanWebsocketAcl', '').split(',')])
+    if config.get('EanWebsocketUrl', '') and request.remote_addr in wsacl:
+        eanwebsocket = config.get('EanWebsocketUrl')
+    else:
+        eanwebsocket = None
     return template.render(
         __version__=__version__,
         notifications=Notification.render(),
+        eanwebsocket=eanwebsocket,
         **kwargs
     ).encode('utf-8')
diff --git a/package/debian/matemat/etc/matemat.conf b/package/debian/matemat/etc/matemat.conf
index b0ba760..09ceab5 100644
--- a/package/debian/matemat/etc/matemat.conf
+++ b/package/debian/matemat/etc/matemat.conf
@@ -38,10 +38,12 @@ InstanceName=Matemat
 #SignupKioskMode= ::1, ::ffff:127.0.0.0/8, 127.0.0.0/8
 
 #
-# Close tabs after completing an EAN code scan based purchase.
-# This only works in Firefox with dom.allow_scripts_to_close_windows=true
+# Open a websocket connection on which to listen for scanned barcodes.
+# Can be restricted so that e.g. the connection is only attempted when the client is localhost.
 #
-#CloseTabAfterEANPurchase=1
+#EanWebsocketUrl=ws://localhost:47808/ws
+#EanWebsocketAcl=::1,::ffff:127.0.0.0/104,127.0.0.0/8
+
 
 # Add static HTTP headers in this section
 # [HttpHeaders]
diff --git a/templates/admin.html b/templates/admin.html
index 7343c6d..f397c46 100644
--- a/templates/admin.html
+++ b/templates/admin.html
@@ -23,3 +23,12 @@
     {{ super() }}
 
 {% endblock %}
+
+{% block eanwebsocket %}
+  function (e) {
+  let eaninput = document.getElementById("admin-newproduct-ean");
+  eaninput.value = e.data;
+  eaninput.select();
+  eaninput.scrollIntoView();
+  }
+{% endblock %}
diff --git a/templates/admin_restricted.html b/templates/admin_restricted.html
index 4581cf0..dc3056e 100644
--- a/templates/admin_restricted.html
+++ b/templates/admin_restricted.html
@@ -17,8 +17,8 @@
         <label for="admin-newuser-isadmin">Admin: </label>
         <input id="admin-newuser-isadmin" type="checkbox" name="isadmin" /><br/>
 
-        <label for="admin-myaccount-logout-after-purchase">Logout after purchase: </label>
-        <input id="admin-myaccount-logout-after-purchase" type="checkbox" name="logout_after_purchase" /><br/>
+        <label for="admin-newuser-logout-after-purchase">Logout after purchase: </label>
+        <input id="admin-newuser-logout-after-purchase" type="checkbox" name="logout_after_purchase" /><br/>
 
         <input type="submit" value="Create User" />
     </form>
diff --git a/templates/base.html b/templates/base.html
index 9134b7e..7609d79 100644
--- a/templates/base.html
+++ b/templates/base.html
@@ -56,5 +56,15 @@
     {% endblock %}
 </footer>
 
+{% if eanwebsocket %}
+<script>
+ function connect() {
+     let socket = new WebSocket("{{ eanwebsocket }}");
+     socket.onclose = () => { setTimeout(connect, 1000); };
+     socket.onmessage = {% block eanwebsocket %}() => {}{% endblock %};
+ }
+ window.addEventListener("load", () => { connect(); });
+</script>
+{% endif %}
 </body>
 </html>
diff --git a/templates/modproduct.html b/templates/modproduct.html
index dc1931e..fcaaba0 100644
--- a/templates/modproduct.html
+++ b/templates/modproduct.html
@@ -52,3 +52,12 @@
 {{ super() }}
 
 {% endblock %}
+
+{% block eanwebsocket %}
+  function (e) {
+  let eaninput = document.getElementById("modproduct-ean");
+  eaninput.value = e.data;
+  eaninput.select();
+  eaninput.scrollIntoView();
+  }
+{% endblock %}
diff --git a/templates/productlist.html b/templates/productlist.html
index 8c3b7ad..5f355f4 100644
--- a/templates/productlist.html
+++ b/templates/productlist.html
@@ -53,7 +53,7 @@
             {% if product.custom_price %}
 	    <a onclick="setup_custom_price({{ product.id }}, '{{ product.name}}');">
 	    {% else %}
-            <a href="/buy?pid={{ product.id }}">
+            <a {% if product.ean %}id="a-buy-ean{{ product.ean }}"{% endif %} href="/buy?pid={{ product.id }}">
 	    {% endif %}
                 <span class="thumblist-title">{{ product.name }}</span>
 		{% if product.custom_price %}
@@ -81,9 +81,15 @@
 
     {{ super() }}
 
-    {% if closetab | default(0) %}
-    {# This only works in Firefox with dom.allow_scripts_to_close_windows=true #}
-    <script>setTimeout(window.close, 3000);</script>
-    {% endif %}
-
+{% endblock %}
+
+{% block eanwebsocket %}
+  function (e) {
+    let eaninput = document.getElementById("a-buy-ean" + e.data);
+    if (eaninput === null) {
+      document.location = "?ean=" + e.data;
+    } else {
+      eaninput.click();
+    }
+  }
 {% endblock %}
diff --git a/templates/userlist.html b/templates/userlist.html
index fedb8be..840ac06 100644
--- a/templates/userlist.html
+++ b/templates/userlist.html
@@ -33,9 +33,10 @@
 
     {{ super() }}
 
-    {% if closetab | default(0) %}
-    {# This only works in Firefox with dom.allow_scripts_to_close_windows=true #}
-    <script>setTimeout(window.close, 3000);</script>
-    {% endif %}
-
+{% endblock %}
+
+{% block eanwebsocket %}
+  function (e) {
+  document.location = "?ean=" + e.data;
+  }
 {% endblock %}