diff --git a/app/MindWork AI Studio/Assistants/I18N/allTexts.lua b/app/MindWork AI Studio/Assistants/I18N/allTexts.lua
index 6d4cc501..715f64af 100644
--- a/app/MindWork AI Studio/Assistants/I18N/allTexts.lua	
+++ b/app/MindWork AI Studio/Assistants/I18N/allTexts.lua	
@@ -1732,6 +1732,9 @@ UI_TEXT_CONTENT["AISTUDIO::CHAT::CONTENTBLOCKCOMPONENT::T4188329028"] = "No, kee
 -- Export Chat to Microsoft Word
 UI_TEXT_CONTENT["AISTUDIO::CHAT::CONTENTBLOCKCOMPONENT::T861873672"] = "Export Chat to Microsoft Word"
 
+-- The selected model '{0}' is no longer available from '{1}' (provider={2}). Please adapt your provider settings.
+UI_TEXT_CONTENT["AISTUDIO::CHAT::CONTENTTEXT::T3267850764"] = "The selected model '{0}' is no longer available from '{1}' (provider={2}). Please adapt your provider settings."
+
 -- The local image file does not exist. Skipping the image.
 UI_TEXT_CONTENT["AISTUDIO::CHAT::IIMAGESOURCEEXTENSIONS::T255679918"] = "The local image file does not exist. Skipping the image."
 
diff --git a/app/MindWork AI Studio/Chat/ContentText.cs b/app/MindWork AI Studio/Chat/ContentText.cs
index 3a9b8f9d..a48e53d5 100644
--- a/app/MindWork AI Studio/Chat/ContentText.cs	
+++ b/app/MindWork AI Studio/Chat/ContentText.cs	
@@ -3,6 +3,8 @@
 
 using AIStudio.Provider;
 using AIStudio.Settings;
+using AIStudio.Tools;
+using AIStudio.Tools.PluginSystem;
 using AIStudio.Tools.RAG.RAGProcesses;
 
 namespace AIStudio.Chat;
@@ -13,6 +15,7 @@ namespace AIStudio.Chat;
 public sealed class ContentText : IContent
 {
     private static readonly ILogger<ContentText> LOGGER = Program.LOGGER_FACTORY.CreateLogger<ContentText>();
+    private static string TB(string fallbackEN) => I18N.I.T(fallbackEN, typeof(ContentText).Namespace, nameof(ContentText));
     
     /// <summary>
     /// The minimum time between two streaming events, when the user
@@ -48,11 +51,21 @@ public sealed class ContentText : IContent
     public async Task<ChatThread> CreateFromProviderAsync(IProvider provider, Model chatModel, IContent? lastUserPrompt, ChatThread? chatThread, CancellationToken token = default)
     {
         if(chatThread is null)
+        {
+            await this.CompleteWithoutStreaming();
             return new();
+        }
         
         if(!chatThread.IsLLMProviderAllowed(provider))
         {
             LOGGER.LogError("The provider is not allowed for this chat thread due to data security reasons. Skipping the AI process.");
+            await this.CompleteWithoutStreaming();
+            return chatThread;
+        }
+
+        if(!await this.CheckSelectedModelAvailability(provider, chatModel, token))
+        {
+            await this.CompleteWithoutStreaming();
             return chatThread;
         }
 
@@ -137,6 +150,67 @@ await Task.Run(async () =>
         return chatThread;
     }
 
+    private async Task CompleteWithoutStreaming()
+    {
+        this.InitialRemoteWait = false;
+        this.IsStreaming = false;
+        await this.StreamingDone();
+    }
+
+    private static bool ModelsMatch(Model modelA, Model modelB)
+    {
+        var idA = modelA.Id.Trim();
+        var idB = modelB.Id.Trim();
+        return string.Equals(idA, idB, StringComparison.OrdinalIgnoreCase);
+    }
+
+    private async Task<bool> CheckSelectedModelAvailability(IProvider provider, Model chatModel, CancellationToken token = default)
+    {
+        if(chatModel.IsSystemModel)
+            return true;
+
+        if (string.IsNullOrWhiteSpace(chatModel.Id))
+        {
+            LOGGER.LogWarning("Skipping AI request because model ID is null or white space.");
+            return false;
+        }
+
+        IEnumerable<Model> loadedModels;
+        try
+        {
+            loadedModels = await provider.GetTextModels(token: token);
+        }
+        catch (OperationCanceledException)
+        {
+            return false;
+        }
+        catch (Exception e)
+        {
+            LOGGER.LogWarning(e, "Skipping selected model availability check for '{ProviderInstanceName}' (provider={ProviderType}) because the model list could not be loaded.", provider.InstanceName, provider.Provider);
+            return true;
+        }
+
+        var availableModels = loadedModels.Where(model => !string.IsNullOrWhiteSpace(model.Id)).ToList();
+        if (availableModels.Count == 0)
+        {
+            LOGGER.LogWarning("Skipping AI request because there are no models available from '{ProviderInstanceName}' (provider={ProviderType}).", provider.InstanceName, provider.Provider);
+            return false;
+        }
+
+        if(availableModels.Any(model => ModelsMatch(model, chatModel)))
+            return true;
+        
+        var message = string.Format(
+            TB("The selected model '{0}' is no longer available from '{1}' (provider={2}). Please adapt your provider settings."),
+            chatModel.Id,
+            provider.InstanceName,
+            provider.Provider);
+        
+        await MessageBus.INSTANCE.SendError(new(Icons.Material.Filled.CloudOff, message));
+        LOGGER.LogWarning("Skipping AI request because model '{ModelId}' is not available from '{ProviderInstanceName}' (provider={ProviderType}).", chatModel.Id, provider.InstanceName, provider.Provider);
+        return false;
+    }
+
     /// <inheritdoc />
     public IContent DeepClone() => new ContentText
     {
@@ -214,4 +288,4 @@ public async Task<string> PrepareTextContentForAI()
     /// The text content.
     /// </summary>
     public string Text { get; set; } = string.Empty;
-}
\ No newline at end of file
+}
diff --git a/app/MindWork AI Studio/Plugins/languages/de-de-43065dbc-78d0-45b7-92be-f14c2926e2dc/plugin.lua b/app/MindWork AI Studio/Plugins/languages/de-de-43065dbc-78d0-45b7-92be-f14c2926e2dc/plugin.lua
index e9571a6c..5cf76278 100644
--- a/app/MindWork AI Studio/Plugins/languages/de-de-43065dbc-78d0-45b7-92be-f14c2926e2dc/plugin.lua	
+++ b/app/MindWork AI Studio/Plugins/languages/de-de-43065dbc-78d0-45b7-92be-f14c2926e2dc/plugin.lua	
@@ -1734,6 +1734,9 @@ UI_TEXT_CONTENT["AISTUDIO::CHAT::CONTENTBLOCKCOMPONENT::T4188329028"] = "Nein, b
 -- Export Chat to Microsoft Word
 UI_TEXT_CONTENT["AISTUDIO::CHAT::CONTENTBLOCKCOMPONENT::T861873672"] = "Chat in Microsoft Word exportieren"
 
+-- The selected model '{0}' is no longer available from '{1}' (provider={2}). Please adapt your provider settings.
+UI_TEXT_CONTENT["AISTUDIO::CHAT::CONTENTTEXT::T3267850764"] = "Das ausgewählte Modell '{0}' ist bei '{1}' (Anbieter={2}) nicht mehr verfügbar. Bitte passen Sie Ihre Anbietereinstellungen an."
+
 -- The local image file does not exist. Skipping the image.
 UI_TEXT_CONTENT["AISTUDIO::CHAT::IIMAGESOURCEEXTENSIONS::T255679918"] = "Die lokale Bilddatei existiert nicht. Das Bild wird übersprungen."
 
diff --git a/app/MindWork AI Studio/Plugins/languages/en-us-97dfb1ba-50c4-4440-8dfa-6575daf543c8/plugin.lua b/app/MindWork AI Studio/Plugins/languages/en-us-97dfb1ba-50c4-4440-8dfa-6575daf543c8/plugin.lua
index 71f6c65a..edd72cc6 100644
--- a/app/MindWork AI Studio/Plugins/languages/en-us-97dfb1ba-50c4-4440-8dfa-6575daf543c8/plugin.lua	
+++ b/app/MindWork AI Studio/Plugins/languages/en-us-97dfb1ba-50c4-4440-8dfa-6575daf543c8/plugin.lua	
@@ -1734,6 +1734,9 @@ UI_TEXT_CONTENT["AISTUDIO::CHAT::CONTENTBLOCKCOMPONENT::T4188329028"] = "No, kee
 -- Export Chat to Microsoft Word
 UI_TEXT_CONTENT["AISTUDIO::CHAT::CONTENTBLOCKCOMPONENT::T861873672"] = "Export Chat to Microsoft Word"
 
+-- The selected model '{0}' is no longer available from '{1}' (provider={2}). Please adapt your provider settings.
+UI_TEXT_CONTENT["AISTUDIO::CHAT::CONTENTTEXT::T3267850764"] = "The selected model '{0}' is no longer available from '{1}' (provider={2}). Please adapt your provider settings."
+
 -- The local image file does not exist. Skipping the image.
 UI_TEXT_CONTENT["AISTUDIO::CHAT::IIMAGESOURCEEXTENSIONS::T255679918"] = "The local image file does not exist. Skipping the image."
 
diff --git a/app/MindWork AI Studio/wwwroot/changelog/v26.3.1.md b/app/MindWork AI Studio/wwwroot/changelog/v26.3.1.md
index 2da8017c..5e4e7791 100644
--- a/app/MindWork AI Studio/wwwroot/changelog/v26.3.1.md	
+++ b/app/MindWork AI Studio/wwwroot/changelog/v26.3.1.md	
@@ -5,6 +5,7 @@
 - Added the ability to format your user prompt in the chat using icons instead of typing Markdown directly.
 - Added the ability to load a system prompt from a file when creating or editing chat templates.
 - Added a start-page setting, so AI Studio can now open directly on your preferred page when the app starts. Configuration plugins can also provide and optionally lock this default for organizations.
+- Added pre-call validation to check if the selected model exists for the provider before making the request.
 - Added math rendering in chats for LaTeX display formulas, including block formats such as `$$ ... $$` and `\[ ... \]`.
 - Released the document analysis assistant after an intense testing phase.
 - Improved the profile selection for assistants and the chat. You can now explicitly choose between the app default profile, no profile, or a specific profile.