diff --git a/src/crypto/algorithms/base.js b/src/crypto/algorithms/base.js
index 1f2434991..40c60a439 100644
--- a/src/crypto/algorithms/base.js
+++ b/src/crypto/algorithms/base.js
@@ -176,8 +176,9 @@ export {DecryptionAlgorithm}; // https://github.com/jsdoc3/jsdoc/issues/1272
  * @extends Error
  */
 class DecryptionError extends Error {
-    constructor(msg, details) {
+    constructor(code, msg, details) {
         super(msg);
+        this.code = code;
         this.name = 'DecryptionError';
         this.detailedString = _detailedStringForDecryptionError(this, details);
     }
diff --git a/src/crypto/algorithms/megolm.js b/src/crypto/algorithms/megolm.js
index 005d157c5..57f6bab32 100644
--- a/src/crypto/algorithms/megolm.js
+++ b/src/crypto/algorithms/megolm.js
@@ -618,7 +618,10 @@ MegolmDecryption.prototype.decryptEvent = async function(event) {
     if (!content.sender_key || !content.session_id ||
         !content.ciphertext
        ) {
-        throw new base.DecryptionError("Missing fields in input");
+        throw new base.DecryptionError(
+            "MEGOLM_MISSING_FIELDS",
+            "Missing fields in input",
+        );
     }
 
     // we add the event to the pending list *before* we start decryption.
@@ -639,6 +642,7 @@ MegolmDecryption.prototype.decryptEvent = async function(event) {
             this._requestKeysForEvent(event);
         }
         throw new base.DecryptionError(
+            "OLM_UNKNOWN_MESSAGE_INDEX",
             e.toString(), {
                 session: content.sender_key + '|' + content.session_id,
             },
@@ -655,6 +659,7 @@ MegolmDecryption.prototype.decryptEvent = async function(event) {
         // scheduled, so we needn't send out the request here.)
         this._requestKeysForEvent(event);
         throw new base.DecryptionError(
+            "MEGOLM_UNKNOWN_INBOUND_SESSION_ID",
             "The sender's device has not sent us the keys for this message.",
             {
                 session: content.sender_key + '|' + content.session_id,
@@ -673,6 +678,7 @@ MegolmDecryption.prototype.decryptEvent = async function(event) {
     // room, so neither the sender nor a MITM can lie about the room_id).
     if (payload.room_id !== event.getRoomId()) {
         throw new base.DecryptionError(
+            "MEGOLM_BAD_ROOM",
             "Message intended for room " + payload.room_id,
         );
     }
diff --git a/src/crypto/algorithms/olm.js b/src/crypto/algorithms/olm.js
index 51b3d1861..b65cb923e 100644
--- a/src/crypto/algorithms/olm.js
+++ b/src/crypto/algorithms/olm.js
@@ -168,11 +168,17 @@ OlmDecryption.prototype.decryptEvent = async function(event) {
     const ciphertext = content.ciphertext;
 
     if (!ciphertext) {
-        throw new base.DecryptionError("Missing ciphertext");
+        throw new base.DecryptionError(
+            "OLM_MISSING_CIPHERTEXT",
+            "Missing ciphertext",
+        );
     }
 
     if (!(this._olmDevice.deviceCurve25519Key in ciphertext)) {
-        throw new base.DecryptionError("Not included in recipients");
+        throw new base.DecryptionError(
+            "OLM_NOT_INCLUDED_IN_RECIPIENTS",
+            "Not included in recipients",
+        );
     }
     const message = ciphertext[this._olmDevice.deviceCurve25519Key];
     let payloadString;
@@ -181,6 +187,7 @@ OlmDecryption.prototype.decryptEvent = async function(event) {
         payloadString = await this._decryptMessage(deviceKey, message);
     } catch (e) {
         throw new base.DecryptionError(
+            "OLM_BAD_ENCRYPTED_MESSAGE",
             "Bad Encrypted Message", {
                 sender: deviceKey,
                 err: e,
@@ -194,12 +201,14 @@ OlmDecryption.prototype.decryptEvent = async function(event) {
     // https://github.com/vector-im/vector-web/issues/2483
     if (payload.recipient != this._userId) {
         throw new base.DecryptionError(
+            "OLM_BAD_RECIPIENT",
             "Message was intented for " + payload.recipient,
         );
     }
 
     if (payload.recipient_keys.ed25519 != this._olmDevice.deviceEd25519Key) {
         throw new base.DecryptionError(
+            "OLM_BAD_RECIPIENT_KEY",
             "Message not intended for this device", {
                 intended: payload.recipient_keys.ed25519,
                 our_key: this._olmDevice.deviceEd25519Key,
@@ -213,6 +222,7 @@ OlmDecryption.prototype.decryptEvent = async function(event) {
     // which is checked elsewhere).
     if (payload.sender != event.getSender()) {
         throw new base.DecryptionError(
+            "OLM_FORWARDED_MESSAGE",
             "Message forwarded from " + payload.sender, {
                 reported_sender: event.getSender(),
             },
@@ -222,6 +232,7 @@ OlmDecryption.prototype.decryptEvent = async function(event) {
     // Olm events intended for a room have a room_id.
     if (payload.room_id !== event.getRoomId()) {
         throw new base.DecryptionError(
+            "OLM_BAD_ROOM",
             "Message intended for room " + payload.room_id, {
                 reported_room: event.room_id,
             },
diff --git a/src/crypto/index.js b/src/crypto/index.js
index 703bd0631..555d98fca 100644
--- a/src/crypto/index.js
+++ b/src/crypto/index.js
@@ -1275,6 +1275,7 @@ Crypto.prototype._getRoomDecryptor = function(roomId, algorithm) {
     const AlgClass = algorithms.DECRYPTION_CLASSES[algorithm];
     if (!AlgClass) {
         throw new algorithms.DecryptionError(
+            'UNKNOWN_ENCRYPTION_ALGORITHM',
             'Unknown encryption algorithm "' + algorithm + '".',
         );
     }
diff --git a/src/models/event.js b/src/models/event.js
index 0bc2a3d40..cde69e1f6 100644
--- a/src/models/event.js
+++ b/src/models/event.js
@@ -451,6 +451,8 @@ utils.extend(module.exports.MatrixEvent.prototype, {
                     `Error decrypting event (id=${this.getId()}): ${e.detailedString}`,
                 );
 
+                console.dir(e);
+
                 res = this._badEncryptedMessage(e.message);
             }