diff --git a/communication/src/errors.js b/communication/src/errors.js
index 5c6d3401..4d6dd007 100644
--- a/communication/src/errors.js
+++ b/communication/src/errors.js
@@ -20,8 +20,8 @@
  * in the code (e.g. configuration errors, incorrect use of the API).
  */
 class ExtendableError extends Error {
-  constructor(message) {
-    super(message);
+  constructor(message, options) {
+    super(message, options);
     this.name = this.constructor.name;
     if (typeof Error.captureStackTrace === 'function') {
       Error.captureStackTrace(this, this.constructor);
@@ -55,8 +55,8 @@ class ExtendableError extends Error {
  *    retried at a later point, or replaced by updated messages.
  */
 class RecoverableError extends ExtendableError {
-  constructor(message) {
-    super(message);
+  constructor(message, options) {
+    super(message, options);
     this.isRecoverableError = true;
     this.isPermanentError = false;
   }
@@ -70,15 +70,26 @@ class RecoverableError extends ExtendableError {
  * trying to send it again will again trigger the identical error.
  */
 class PermanentError extends ExtendableError {
-  constructor(message) {
-    super(message);
+  constructor(message, options) {
+    super(message, options);
     this.isRecoverableError = false;
     this.isPermanentError = true;
   }
 }
 
+/**
+ * The message size exceeded the limit of 32K.
+ */
 export class TooBigMsgError extends PermanentError {}
+
 export class TransportError extends RecoverableError {}
 export class ProtocolError extends PermanentError {}
 export class InvalidMessageError extends PermanentError {}
 export class ClockOutOfSync extends RecoverableError {}
+
+/**
+ * Thrown when the client failed to fetch public keys. Without
+ * current keys, it cannot setup the end-to-end encryption
+ * needed to communicate with the server.
+ */
+export class FailedToFetchPublicKeys extends RecoverableError {}
diff --git a/communication/src/server-public-key-accessor.js b/communication/src/server-public-key-accessor.js
index b7843f52..2d505dd8 100644
--- a/communication/src/server-public-key-accessor.js
+++ b/communication/src/server-public-key-accessor.js
@@ -12,6 +12,7 @@
 import logger from './logger.js';
 import { getTimeAsYYYYMMDD } from './timestamps.js';
 import { fromBase64 } from './encoding.js';
+import { FailedToFetchPublicKeys } from './errors.js';
 
 function isYYYYMMDD(date) {
   return typeof date === 'string' && /^[0-9]{8}$/.test(date);
@@ -72,21 +73,7 @@ export default class ServerPublicKeyAccessor {
 
     // not found on disk or outdated -> fetch from server
     if (!knownKeys) {
-      const url = `${this.collectorUrl}/config?fields=pubKeys`;
-      logger.info('Fetching new server public keys from', url);
-      const response = await fetch(url, {
-        method: 'GET',
-        credentials: 'omit',
-        redirect: 'manual',
-      });
-      if (!response.ok) {
-        throw new Error(
-          `Failed to get config (${response.statusText}) from url=${url}`,
-        );
-      }
-      const { pubKeys } = await response.json();
-      logger.info('Fetched server public keys:', pubKeys);
-
+      const pubKeys = await this._fetchPublicKeys();
       const allKeys = Object.keys(pubKeys)
         .filter(isYYYYMMDD)
         .map((date) => [date, fromBase64(pubKeys[date])]);
@@ -104,6 +91,31 @@ export default class ServerPublicKeyAccessor {
     this._knownKeys = knownKeys;
   }
 
+  async _fetchPublicKeys() {
+    const url = `${this.collectorUrl}/config?fields=pubKeys`;
+    logger.info('Fetching new server public keys from', url);
+    try {
+      const response = await fetch(url, {
+        method: 'GET',
+        credentials: 'omit',
+        redirect: 'manual',
+      });
+      if (!response.ok) {
+        throw new Error(
+          `Failed to get config (${response.statusText}) from '${url}'`,
+        );
+      }
+      const { pubKeys } = await response.json();
+      logger.info('Fetched server public keys:', pubKeys);
+      return pubKeys;
+    } catch (e) {
+      throw new FailedToFetchPublicKeys(
+        `Failed to fetch public keys from '${url}'`,
+        { cause: e },
+      );
+    }
+  }
+
   async importAndVerifyPubKeys(allKeys) {
     return new Map(
       await Promise.all(