diff --git a/src/components/structures/MatrixChat.js b/src/components/structures/MatrixChat.js
index cd75ad87981..6c192564b29 100644
--- a/src/components/structures/MatrixChat.js
+++ b/src/components/structures/MatrixChat.js
@@ -1142,6 +1142,37 @@ module.exports = React.createClass({
                 room.setBlacklistUnverifiedDevices(blacklistEnabled);
             }
         });
+        cli.on("crypto.warning", (type) => {
+            const ErrorDialog = sdk.getComponent("dialogs.ErrorDialog");
+            switch (type) {
+                case 'CRYPTO_WARNING_ACCOUNT_MIGRATED':
+                    Modal.createTrackedDialog('Crypto migrated', '', ErrorDialog, {
+                        title: _t('Cryptography data migrated'),
+                        description: _t(
+                            "A one-off migration of cryptography data has been performed. "+
+                            "End-to-end encryption will not work if you go back to an older "+
+                            "version of Riot. If you need to use end-to-end cryptography on "+
+                            "an older version, log out of Riot first. To retain message history, "+
+                            "export and re-import your keys.",
+                        ),
+                    });
+                    break;
+                case 'CRYPTO_WARNING_OLD_VERSION_DETECTED':
+                    Modal.createTrackedDialog('Crypto migrated', '', ErrorDialog, {
+                        title: _t('Old cryptography data detected'),
+                        description: _t(
+                            "Data from an older version of Riot has been detected. "+
+                            "This will have caused end-to-end cryptography to malfunction "+
+                            "in the older version. End-to-end encrypted messages exchanged "+
+                            "recently whilst using the older version may not be decryptable "+
+                            "in this version. This may also cause messages exchanged with this "+
+                            "version to fail. If you experience problems, log out and back in "+
+                            "again. To retain message history, export and re-import your keys.",
+                        ),
+                    });
+                    break;
+            }
+        });
     },
 
     /**
diff --git a/src/i18n/strings/en_EN.json b/src/i18n/strings/en_EN.json
index d632692e046..ad722779562 100644
--- a/src/i18n/strings/en_EN.json
+++ b/src/i18n/strings/en_EN.json
@@ -748,6 +748,10 @@
     "Failed to leave room": "Failed to leave room",
     "Signed Out": "Signed Out",
     "For security, this session has been signed out. Please sign in again.": "For security, this session has been signed out. Please sign in again.",
+    "Cryptography data migrated": "Cryptography data migrated",
+    "A one-off migration of cryptography data has been performed. End-to-end encryption will not work if you go back to an older version of Riot. If you need to use end-to-end cryptography on an older version, log out of Riot first. To retain message history, export and re-import your keys.": "A one-off migration of cryptography data has been performed. End-to-end encryption will not work if you go back to an older version of Riot. If you need to use end-to-end cryptography on an older version, log out of Riot first. To retain message history, export and re-import your keys.",
+    "Old cryptography data detected": "Old cryptography data detected",
+    "Data from an older version of Riot has been detected. This will have caused end-to-end cryptography to malfunction in the older version. End-to-end encrypted messages exchanged recently whilst using the older version may not be decryptable in this version. This may also cause messages exchanged with this version to fail. If you experience problems, log out and back in again. To retain message history, export and re-import your keys.": "Data from an older version of Riot has been detected. This will have caused end-to-end cryptography to malfunction in the older version. End-to-end encrypted messages exchanged recently whilst using the older version may not be decryptable in this version. This may also cause messages exchanged with this version to fail. If you experience problems, log out and back in again. To retain message history, export and re-import your keys.",
     "Logout": "Logout",
     "Your Communities": "Your Communities",
     "Error whilst fetching joined communities": "Error whilst fetching joined communities",