diff --git a/noise/public/javascripts/chart_utilities.js b/noise/public/javascripts/chart_utilities.js
index aa4ce2b..40770f4 100644
--- a/noise/public/javascripts/chart_utilities.js
+++ b/noise/public/javascripts/chart_utilities.js
@@ -255,14 +255,17 @@ export const addAddress = async (sid) => {
     }
 }
 
+// liefert {coords: [lat, lon], err: null} oder {coords: null, err: <Meldung>}.
+// Kein Ersatzwert wie frueher "no coordinates": der Aufrufer muss den Fehlschlag
+// erkennen koennen, sonst landet ein ungueltiges Zentrum in der Karte und
+// Leaflet baut sie nicht mehr auf (graues Fenster).
 export const cityCoords = async (city) => {
     let url = `/srv/getcitycoords?city=${city}`
     let erg = await fetchfromserver(url)
-    if (!erg.err) {
-        return erg.coords
-    } else {
-        return "no coordinates"
+    if (erg.err || !Array.isArray(erg.coords) || erg.coords.length !== 2) {
+        return {coords: null, err: erg.err || `'${city}' ?`}
     }
+    return {coords: erg.coords, err: null}
 }
 
 // table to distribute the different charts
diff --git a/noise/public/javascripts/global.js b/noise/public/javascripts/global.js
index d7edd60..28345f0 100644
--- a/noise/public/javascripts/global.js
+++ b/noise/public/javascripts/global.js
@@ -86,6 +86,7 @@ import * as spin from './spinner.js'
     // Button 'Save' pressed
     document.querySelector('#btnSave').addEventListener('click', async () => {
         let curtab =  getCurrentTab()
+        let cityErr = null                            // Meldung erst nach dem Schliessen des Dialogs zeigen
         for(let i = 0; i < setting.length; i++) {
             if(setting[i].typ === getCurrentTab()) {
                 for(let j = 0; j < setting[i].show.length; j++) {
@@ -115,9 +116,17 @@ import * as spin from './spinner.js'
             params.datetime = starttime
         } else {
             const oldCoords = params.center.coords
-            params.center.coords = await cityCoords(params.center.name)
-            checkNewCenter(oldCoords, params.center.coords)
-            localStorage.setItem('centercity',JSON.stringify(params.center))
+            const erg = await cityCoords(params.center.name)
+            if (erg.coords === null) {
+                // Ort nicht aufloesbar: altes Zentrum behalten. Ohne das landet
+                // ein ungueltiger Wert in setView() und die Karte bleibt grau.
+                cityErr = erg.err
+                params.center = JSON.parse(localStorage.getItem('centercity'))
+            } else {
+                params.center.coords = erg.coords
+                checkNewCenter(oldCoords, params.center.coords)
+                localStorage.setItem('centercity',JSON.stringify(params.center))
+            }
         }
         let newlng = document.querySelector('#sellan input:checked').id
         let oldlng = localStorage.getItem('curlang')
@@ -129,6 +138,9 @@ import * as spin from './spinner.js'
         spin.spinner.spin(spin.spindiv)
         await loadAll(params,0, curtab)
         spin.spinner.stop()
+        if (cityErr) {
+            showError(cityErr)
+        }
         // ToDo:
         // Load ALL incl. MAP und LIVE hier, d.h. an loadAll einen zusätzlichen Parameter übergeben
         // if(params.sid !== undefined) {
diff --git a/noise/routes/api.js b/noise/routes/api.js
index 24c9202..c3df57f 100644
--- a/noise/routes/api.js
+++ b/noise/routes/api.js
@@ -29,7 +29,10 @@ router.get('/:cmd', async function(req, res, next) {
 
   let url = APIHOST + '/api' + req.originalUrl.slice(4) + `&lng=${lng}`
   try {
-    const response = await axios.get(encodeURI(url) , {
+    // kein encodeURI: req.originalUrl ist bereits prozentkodiert. Ein zweiter
+    // Durchlauf macht aus '%C3%B6' ein '%25C3%25B6', und die Gegenseite sieht
+    // dann den Text 'G%c3%b6ttingen' statt 'Göttingen'.
+    const response = await axios.get(url , {
       headers: {'X-API-Key': API_KEY}
     });
     if (response.status !== 200) {
diff --git a/sensorapi/actions/getaddress.js b/sensorapi/actions/getaddress.js
index eecf128..84e4e40 100644
--- a/sensorapi/actions/getaddress.js
+++ b/sensorapi/actions/getaddress.js
@@ -6,17 +6,27 @@ import { response } from "express"
 
 const NOMINATIM_URL = `https://nominatim.openstreetmap.org/reverse?lat=${'xx'}&lon=${'yy'}&format=json`
 const NOMINATIM_CITY_URL = `https://nominatim.openstreetmap.org/?q="${'xx'}"&format=json`
+// Nominatim verlangt laut Nutzungsbedingungen einen eigenen User-Agent und
+// beantwortet den Default von axios ('axios/1.x') mit 403.
+const NOMINATIM_UA = 'laermsensor-stack (rxf@gmx.de)'
 
 export const getCityCoords = async (params) => {
     let ret = {coords: [], city: params.city, err: null}
     let url = NOMINATIM_CITY_URL.replace('xx', params.city)
 //    let url = 'https://nominatim.openstreetmap.org/?q="K%C3%B6ln"&format=json'
     try {
-        const response = await axios(url)
+        const response = await axios(encodeURI(url), {
+            headers: {
+                'User-Agent': NOMINATIM_UA
+            }
+        })
         if (response.status !== 200) {
-            return returnOnError(ret, 'RESPSTATUS', getCityCoord.name, response.status)
+            return returnOnError(ret, 'RESPSTATUS', getCityCoords.name, response.status)
         }
-        ret.coords = [response.data[0].lat,response.data[0].lon]
+        if (!response.data.length) {                    // Stadt nicht gefunden
+            return returnOnError(ret, 'ENOCITY', getCityCoords.name, params.city)
+        }
+        ret.coords = [parseFloat(response.data[0].lat), parseFloat(response.data[0].lon)]
         logit(JSON.stringify(ret.coords))
     } catch (e) {
         return returnOnError(ret, e, getCityCoords.name)
@@ -35,7 +45,7 @@ export const getAddress = async (params) => {
     try {
         const response = await axios(encodeURI(url),{
             headers: {
-                'User-Agent': 'Firefox 132.0.1'
+                'User-Agent': NOMINATIM_UA
             }
         });
         if (response.status !== 200) {
diff --git a/sensorapi/locales/de/translation.json b/sensorapi/locales/de/translation.json
index bd7b225..ffa9399 100644
--- a/sensorapi/locales/de/translation.json
+++ b/sensorapi/locales/de/translation.json
@@ -12,5 +12,6 @@
   "SYNTAXURL": "Syntax Fehler beim Aufruf der URL",
   "WRONGTYPE": "Sensor xxx ist kein yyy Sensor",
   "NOLASTDATES": "Probleme bein abholen der letzten Daten",
-  "NOPROPSFOUND": "Properties Collection nicht gefunden"
+  "NOPROPSFOUND": "Properties Collection nicht gefunden",
+  "ENOCITY": "Ort \"xxx\" nicht gefunden"
 }
diff --git a/sensorapi/locales/en/translation.json b/sensorapi/locales/en/translation.json
index d701d6d..f4d9bd0 100644
--- a/sensorapi/locales/en/translation.json
+++ b/sensorapi/locales/en/translation.json
@@ -12,5 +12,6 @@
   "SYNTAXURL": "Syntax error in calling url!",
   "WRONGTYPE": "Sensor xxx is not of type yyy",
   "NOLASTDATES": "Problems fetching last dates from database",
-  "NOPROPSFOUND": "Properties collection not found"
+  "NOPROPSFOUND": "Properties collection not found",
+  "ENOCITY": "City 'xxx' not found"
 }