diff --git a/native/account/fullscreen-siwe-panel.react.js b/native/account/fullscreen-siwe-panel.react.js
--- a/native/account/fullscreen-siwe-panel.react.js
+++ b/native/account/fullscreen-siwe-panel.react.js
@@ -107,10 +107,10 @@
               );
             } catch (e) {
               const messageForException = getMessageForException(e);
-              if (messageForException === 'nonce expired') {
+              if (messageForException === 'nonce_expired') {
                 onNonceExpired('login');
               } else if (
-                messageForException === 'Unsupported version' ||
+                messageForException === 'unsupported_version' ||
                 messageForException === 'client_version_unsupported'
               ) {
                 Alert.alert(
diff --git a/native/account/log-in-panel.react.js b/native/account/log-in-panel.react.js
--- a/native/account/log-in-panel.react.js
+++ b/native/account/log-in-panel.react.js
@@ -349,7 +349,7 @@
           { cancelable: false },
         );
       } else if (
-        messageForException === 'Unsupported version' ||
+        messageForException === 'unsupported_version' ||
         messageForException === 'client_version_unsupported'
       ) {
         Alert.alert(
diff --git a/native/account/registration/existing-ethereum-account.react.js b/native/account/registration/existing-ethereum-account.react.js
--- a/native/account/registration/existing-ethereum-account.react.js
+++ b/native/account/registration/existing-ethereum-account.react.js
@@ -82,7 +82,7 @@
       }
     } catch (e) {
       const messageForException = getMessageForException(e);
-      if (messageForException === 'nonce expired') {
+      if (messageForException === 'nonce_expired') {
         setCachedSelections(oldUserSelections => ({
           ...oldUserSelections,
           ethereumAccount: undefined,
@@ -96,7 +96,7 @@
           },
         );
       } else if (
-        messageForException === 'Unsupported version' ||
+        messageForException === 'unsupported_version' ||
         messageForException === 'client_version_unsupported'
       ) {
         Alert.alert(
diff --git a/native/account/registration/registration-server-call.js b/native/account/registration/registration-server-call.js
--- a/native/account/registration/registration-server-call.js
+++ b/native/account/registration/registration-server-call.js
@@ -133,7 +133,7 @@
               [{ text: 'OK', onPress: onAlertAcknowledged }],
               { cancelable: !onAlertAcknowledged },
             );
-          } else if (messageForException === 'Unsupported version') {
+          } else if (messageForException === 'unsupported_version') {
             Alert.alert(
               appOutOfDateAlertDetails.title,
               appOutOfDateAlertDetails.message,
@@ -277,9 +277,9 @@
         });
       } catch (e) {
         const messageForException = getMessageForException(e);
-        if (messageForException === 'nonce expired') {
+        if (messageForException === 'nonce_expired') {
           onNonceExpired();
-        } else if (messageForException === 'Unsupported version') {
+        } else if (messageForException === 'unsupported_version') {
           Alert.alert(
             appOutOfDateAlertDetails.title,
             appOutOfDateAlertDetails.message,
diff --git a/native/qr-code/qr-code-screen.react.js b/native/qr-code/qr-code-screen.react.js
--- a/native/qr-code/qr-code-screen.react.js
+++ b/native/qr-code/qr-code-screen.react.js
@@ -75,7 +75,7 @@
         const messageForException = getMessageForException(err);
         if (
           messageForException === 'client_version_unsupported' ||
-          messageForException === 'Unsupported version'
+          messageForException === 'unsupported_version'
         ) {
           Alert.alert(
             appOutOfDateAlertDetails.title,
diff --git a/services/identity/src/client_service.rs b/services/identity/src/client_service.rs
--- a/services/identity/src/client_service.rs
+++ b/services/identity/src/client_service.rs
@@ -549,11 +549,17 @@
       .await
       .map_err(handle_db_error)?
     {
-      None => return Err(tonic::Status::invalid_argument("invalid nonce")),
+      None => {
+        return Err(tonic::Status::invalid_argument(
+          tonic_status_messages::INVALID_NONCE,
+        ))
+      }
       Some(nonce) if nonce.is_expired() => {
         // we don't need to remove the nonce from the table here
         // because the DynamoDB TTL will take care of it
-        return Err(tonic::Status::aborted("nonce expired"));
+        return Err(tonic::Status::aborted(
+          tonic_status_messages::NONCE_EXPIRED,
+        ));
       }
       Some(_) => self
         .client
@@ -1073,11 +1079,17 @@
       .await
       .map_err(handle_db_error)?
     {
-      None => return Err(tonic::Status::invalid_argument("invalid nonce")),
+      None => {
+        return Err(tonic::Status::invalid_argument(
+          tonic_status_messages::INVALID_NONCE,
+        ))
+      }
       Some(nonce) if nonce.is_expired() => {
         // we don't need to remove the nonce from the table here
         // because the DynamoDB TTL will take care of it
-        return Err(tonic::Status::aborted("nonce expired"));
+        return Err(tonic::Status::aborted(
+          tonic_status_messages::NONCE_EXPIRED,
+        ));
       }
       Some(nonce_data) => self
         .client
diff --git a/services/identity/src/constants.rs b/services/identity/src/constants.rs
--- a/services/identity/src/constants.rs
+++ b/services/identity/src/constants.rs
@@ -231,6 +231,8 @@
   pub const WALLET_ADDRESS_TAKEN: &str = "wallet_address_taken";
   pub const WALLET_ADDRESS_NOT_RESERVED: &str = "wallet_address_not_reserved";
   pub const USER_NOT_FOUND: &str = "user_not_found";
+  pub const INVALID_NONCE: &str = "invalid_nonce";
+  pub const NONCE_EXPIRED: &str = "nonce_expired";
 }
 
 // Tunnelbroker
diff --git a/shared/grpc_clients/src/error.rs b/shared/grpc_clients/src/error.rs
--- a/shared/grpc_clients/src/error.rs
+++ b/shared/grpc_clients/src/error.rs
@@ -15,10 +15,10 @@
 }
 
 pub fn unsupported_version() -> Status {
-  Status::unimplemented("Unsupported version")
+  Status::unimplemented("unsupported_version")
 }
 
 pub fn is_version_unsupported(status: &Status) -> bool {
   status.code() == Code::Unimplemented
-    && status.message() == "Unsupported version"
+    && status.message() == "unsupported_version"
 }
diff --git a/web/account/qr-code-login.react.js b/web/account/qr-code-login.react.js
--- a/web/account/qr-code-login.react.js
+++ b/web/account/qr-code-login.react.js
@@ -98,7 +98,7 @@
         const messageForException = getMessageForException(err);
         if (
           messageForException === 'client_version_unsupported' ||
-          messageForException === 'Unsupported version'
+          messageForException === 'unsupported_version'
         ) {
           pushModal(<VersionUnsupportedModal />);
         } else {
diff --git a/web/account/siwe-login-form.react.js b/web/account/siwe-login-form.react.js
--- a/web/account/siwe-login-form.react.js
+++ b/web/account/siwe-login-form.react.js
@@ -178,7 +178,7 @@
           setError('account_does_not_exist');
         } else if (
           messageForException === 'client_version_unsupported' ||
-          messageForException === 'Unsupported version'
+          messageForException === 'unsupported_version'
         ) {
           setError('client_version_unsupported');
         }
diff --git a/web/account/traditional-login-form.react.js b/web/account/traditional-login-form.react.js
--- a/web/account/traditional-login-form.react.js
+++ b/web/account/traditional-login-form.react.js
@@ -134,7 +134,7 @@
         setErrorMessage('incorrect username or password');
       } else if (
         messageForException === 'client_version_unsupported' ||
-        messageForException === 'Unsupported version'
+        messageForException === 'unsupported_version'
       ) {
         setErrorMessage(getShortVersionUnsupportedError());
       } else {