diff --git a/app/src/main/java/com/x8bit/bitwarden/data/auth/datasource/network/model/GetTokenResponseJson.kt b/app/src/main/java/com/x8bit/bitwarden/data/auth/datasource/network/model/GetTokenResponseJson.kt
index 636b9a8a9..ee25582af 100644
--- a/app/src/main/java/com/x8bit/bitwarden/data/auth/datasource/network/model/GetTokenResponseJson.kt
+++ b/app/src/main/java/com/x8bit/bitwarden/data/auth/datasource/network/model/GetTokenResponseJson.kt
@@ -96,9 +96,17 @@ sealed class GetTokenResponseJson {
     @Serializable
     data class Invalid(
         @SerialName("ErrorModel")
-        val errorModel: ErrorModel,
+        val errorModel: ErrorModel?,
+        @SerialName("errorModel")
+        val legacyErrorModel: LegacyErrorModel?,
     ) : GetTokenResponseJson() {
 
+        /**
+         * The error message returned from the server, or null.
+         */
+        val errorMessage: String?
+            get() = errorModel?.errorMessage ?: legacyErrorModel?.errorMessage
+
         /**
          * The error body of an invalid request containing a message.
          */
@@ -107,6 +115,18 @@ sealed class GetTokenResponseJson {
             @SerialName("Message")
             val errorMessage: String,
         )
+
+        /**
+         * The legacy error body of an invalid request containing a message.
+         *
+         * This model is used to support older versions of the error response model that used
+         * lower-case keys.
+         */
+        @Serializable
+        data class LegacyErrorModel(
+            @SerialName("message")
+            val errorMessage: String,
+        )
     }
 
     /**
diff --git a/app/src/main/java/com/x8bit/bitwarden/data/auth/repository/AuthRepositoryImpl.kt b/app/src/main/java/com/x8bit/bitwarden/data/auth/repository/AuthRepositoryImpl.kt
index 0b369b6d3..747f60163 100644
--- a/app/src/main/java/com/x8bit/bitwarden/data/auth/repository/AuthRepositoryImpl.kt
+++ b/app/src/main/java/com/x8bit/bitwarden/data/auth/repository/AuthRepositoryImpl.kt
@@ -45,7 +45,6 @@ import com.x8bit.bitwarden.data.auth.repository.model.AuthState
 import com.x8bit.bitwarden.data.auth.repository.model.BreachCountResult
 import com.x8bit.bitwarden.data.auth.repository.model.DeleteAccountResult
 import com.x8bit.bitwarden.data.auth.repository.model.EmailTokenResult
-import com.x8bit.bitwarden.data.platform.manager.model.FirstTimeState
 import com.x8bit.bitwarden.data.auth.repository.model.KnownDeviceResult
 import com.x8bit.bitwarden.data.auth.repository.model.LoginResult
 import com.x8bit.bitwarden.data.auth.repository.model.NewSsoUserResult
@@ -99,6 +98,7 @@ import com.x8bit.bitwarden.data.platform.manager.FirstTimeActionManager
 import com.x8bit.bitwarden.data.platform.manager.PolicyManager
 import com.x8bit.bitwarden.data.platform.manager.PushManager
 import com.x8bit.bitwarden.data.platform.manager.dispatcher.DispatcherManager
+import com.x8bit.bitwarden.data.platform.manager.model.FirstTimeState
 import com.x8bit.bitwarden.data.platform.manager.model.FlagKey
 import com.x8bit.bitwarden.data.platform.manager.util.getActivePolicies
 import com.x8bit.bitwarden.data.platform.repository.EnvironmentRepository
@@ -1503,7 +1503,7 @@ class AuthRepositoryImpl(
                     )
 
                     is GetTokenResponseJson.Invalid -> LoginResult.Error(
-                        errorMessage = loginResponse.errorModel.errorMessage,
+                        errorMessage = loginResponse.errorMessage,
                     )
                 }
             },
diff --git a/app/src/test/java/com/x8bit/bitwarden/data/auth/datasource/network/service/IdentityServiceTest.kt b/app/src/test/java/com/x8bit/bitwarden/data/auth/datasource/network/service/IdentityServiceTest.kt
index 50d92b082..90d64d205 100644
--- a/app/src/test/java/com/x8bit/bitwarden/data/auth/datasource/network/service/IdentityServiceTest.kt
+++ b/app/src/test/java/com/x8bit/bitwarden/data/auth/datasource/network/service/IdentityServiceTest.kt
@@ -273,6 +273,22 @@ class IdentityServiceTest : BaseServiceTest() {
         assertEquals(INVALID_LOGIN.asSuccess(), result)
     }
 
+    @Test
+    fun `getToken when response is a 400 with a legacy error body should return Invalid`() =
+        runTest {
+            server.enqueue(MockResponse().setResponseCode(400).setBody(LEGACY_INVALID_LOGIN_JSON))
+            val result = identityService.getToken(
+                email = EMAIL,
+                authModel = IdentityTokenAuthModel.MasterPassword(
+                    username = EMAIL,
+                    password = PASSWORD_HASH,
+                ),
+                captchaToken = null,
+                uniqueAppId = UNIQUE_APP_ID,
+            )
+            assertEquals(LEGACY_INVALID_LOGIN.asSuccess(), result)
+        }
+
     @Test
     fun `prevalidateSso when response is success should return PrevalidateSsoResponseJson`() =
         runTest {
@@ -613,6 +629,14 @@ private const val INVALID_LOGIN_JSON = """
 }
 """
 
+private const val LEGACY_INVALID_LOGIN_JSON = """
+{
+  "errorModel": {
+    "message": "Legacy-123"
+  }
+}
+"""
+
 private const val TOO_MANY_REQUEST_ERROR_JSON = """
 {
   "Object": "error",
@@ -645,6 +669,14 @@ private val INVALID_LOGIN = GetTokenResponseJson.Invalid(
     errorModel = GetTokenResponseJson.Invalid.ErrorModel(
         errorMessage = "123",
     ),
+    legacyErrorModel = null,
+)
+
+private val LEGACY_INVALID_LOGIN = GetTokenResponseJson.Invalid(
+    errorModel = null,
+    legacyErrorModel = GetTokenResponseJson.Invalid.LegacyErrorModel(
+        errorMessage = "Legacy-123",
+    ),
 )
 
 private val SEND_VERIFICATION_EMAIL_REQUEST = SendVerificationEmailRequestJson(
diff --git a/app/src/test/java/com/x8bit/bitwarden/data/auth/repository/AuthRepositoryTest.kt b/app/src/test/java/com/x8bit/bitwarden/data/auth/repository/AuthRepositoryTest.kt
index 162ba1851..12336587b 100644
--- a/app/src/test/java/com/x8bit/bitwarden/data/auth/repository/AuthRepositoryTest.kt
+++ b/app/src/test/java/com/x8bit/bitwarden/data/auth/repository/AuthRepositoryTest.kt
@@ -65,7 +65,6 @@ import com.x8bit.bitwarden.data.auth.repository.model.AuthState
 import com.x8bit.bitwarden.data.auth.repository.model.BreachCountResult
 import com.x8bit.bitwarden.data.auth.repository.model.DeleteAccountResult
 import com.x8bit.bitwarden.data.auth.repository.model.EmailTokenResult
-import com.x8bit.bitwarden.data.platform.manager.model.FirstTimeState
 import com.x8bit.bitwarden.data.auth.repository.model.KnownDeviceResult
 import com.x8bit.bitwarden.data.auth.repository.model.LoginResult
 import com.x8bit.bitwarden.data.auth.repository.model.NewSsoUserResult
@@ -106,6 +105,7 @@ import com.x8bit.bitwarden.data.platform.manager.FirstTimeActionManager
 import com.x8bit.bitwarden.data.platform.manager.PolicyManager
 import com.x8bit.bitwarden.data.platform.manager.PushManager
 import com.x8bit.bitwarden.data.platform.manager.dispatcher.DispatcherManager
+import com.x8bit.bitwarden.data.platform.manager.model.FirstTimeState
 import com.x8bit.bitwarden.data.platform.manager.model.FlagKey
 import com.x8bit.bitwarden.data.platform.manager.model.NotificationLogoutData
 import com.x8bit.bitwarden.data.platform.repository.SettingsRepository
@@ -1522,6 +1522,7 @@ class AuthRepositoryTest {
                 errorModel = GetTokenResponseJson.Invalid.ErrorModel(
                     errorMessage = "mock_error_message",
                 ),
+                legacyErrorModel = null,
             )
             .asSuccess()
 
@@ -2314,6 +2315,7 @@ class AuthRepositoryTest {
                     errorModel = GetTokenResponseJson.Invalid.ErrorModel(
                         errorMessage = "mock_error_message",
                     ),
+                    legacyErrorModel = null,
                 )
                 .asSuccess()
 
@@ -2782,6 +2784,7 @@ class AuthRepositoryTest {
                 errorModel = GetTokenResponseJson.Invalid.ErrorModel(
                     errorMessage = "mock_error_message",
                 ),
+                legacyErrorModel = null,
             )
             .asSuccess()