diff --git a/CHANGELOG.md b/CHANGELOG.md
index 74a076dad5..8e2309f77b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -58,6 +58,8 @@ and this project adheres to
 
 ### Fixed
 
+- Fix canvas "lockup" after AI chat errors, prevent sending empty message to AI
+  [3605](https://github.com/OpenFn/lightning/issues/3605)
 - Fix memory bloat on dataclip viewer in dataclip detail page
   [#3641](https://github.com/OpenFn/lightning/issues/3641)
 - Ameliorate memory usage when scrubbing dataclips for security
diff --git a/lib/lightning_web/live/ai_assistant/component.ex b/lib/lightning_web/live/ai_assistant/component.ex
index be74472fbe..1b8e5dfcac 100644
--- a/lib/lightning_web/live/ai_assistant/component.ex
+++ b/lib/lightning_web/live/ai_assistant/component.ex
@@ -250,6 +250,7 @@ defmodule LightningWeb.AiAssistant.Component do
         socket
       ) do
     cleared_params = Map.put(params, "content", nil)
+    trimmed_content = if is_binary(content), do: String.trim(content), else: ""
 
     cond do
       not socket.assigns.can_edit ->
@@ -263,6 +264,23 @@ defmodule LightningWeb.AiAssistant.Component do
       socket.assigns.ai_limit_result != :ok ->
         {:noreply, socket}
 
+      trimmed_content == "" ->
+        changeset = socket.assigns.handler.validate_form(%{"content" => ""})
+
+        changeset =
+          Ecto.Changeset.add_error(
+            changeset,
+            :content,
+            "Please enter a message before sending"
+          )
+
+        {:noreply,
+         socket
+         |> assign(
+           changeset: changeset,
+           alert: "Please enter a message before sending"
+         )}
+
       true ->
         {:noreply,
          socket
@@ -272,7 +290,7 @@ defmodule LightningWeb.AiAssistant.Component do
            :changeset,
            socket.assigns.handler.validate_form(cleared_params)
          )
-         |> save_message(socket.assigns.action, content)}
+         |> save_message(socket.assigns.action, trimmed_content)}
     end
   end
 
@@ -447,7 +465,9 @@ defmodule LightningWeb.AiAssistant.Component do
   end
 
   defp handle_save_error(socket, error) do
-    assign(socket, alert: socket.assigns.handler.error_message(error))
+    socket
+    |> assign(alert: socket.assigns.handler.error_message(error))
+    |> assign(pending_message: AsyncResult.ok(nil))
   end
 
   defp redirect_url(base_url, query_params) do
@@ -679,11 +699,11 @@ defmodule LightningWeb.AiAssistant.Component do
           <.simple_button_with_tooltip
             id={"ai-assistant-form-submit-btn-#{@id}"}
             type="submit"
-            disabled={@disabled}
+            disabled={@disabled || form_content_empty?(@form[:content].value)}
             form={@form_id}
             class={[
               "p-1.5 rounded-full focus:outline-none focus:ring-2 focus:ring-offset-2 transition-all duration-200 flex items-center justify-center h-7 w-7",
-              if(@disabled,
+              if(@disabled || form_content_empty?(@form[:content].value),
                 do:
                   "text-gray-400 bg-gray-300 cursor-not-allowed focus:ring-gray-300",
                 else:
@@ -933,6 +953,15 @@ defmodule LightningWeb.AiAssistant.Component do
     Timex.diff(DateTime.utc_now(), datetime, :hours) < 1
   end
 
+  defp form_content_empty?(value) do
+    case value do
+      nil -> true
+      "" -> true
+      content when is_binary(content) -> String.trim(content) == ""
+      _ -> false
+    end
+  end
+
   defp render_onboarding(assigns) do
     assigns = assign(assigns, ai_quote: Quotes.random_enabled())
 
diff --git a/lib/lightning_web/live/ai_assistant/mode_behavior.ex b/lib/lightning_web/live/ai_assistant/mode_behavior.ex
index 99cd4d65d9..188cd152f7 100644
--- a/lib/lightning_web/live/ai_assistant/mode_behavior.ex
+++ b/lib/lightning_web/live/ai_assistant/mode_behavior.ex
@@ -233,11 +233,20 @@ defmodule LightningWeb.Live.AiAssistant.ModeBehavior do
           field :content, :string
         end
 
-        def changeset(params) do
+        @doc false
+        def changeset(params \\ %{}) do
           %__MODULE__{}
           |> cast(params, [:content])
+          |> validate_required([:content],
+            message: "Please enter a message before sending"
+          )
+          |> validate_length(:content,
+            min: 1,
+            message: "Please enter a message before sending"
+          )
         end
 
+        @doc false
         def extract_options(_changeset), do: []
       end
 
diff --git a/lib/lightning_web/live/ai_assistant/modes/job_code.ex b/lib/lightning_web/live/ai_assistant/modes/job_code.ex
index 1bc71b5cc3..8cc2fc2073 100644
--- a/lib/lightning_web/live/ai_assistant/modes/job_code.ex
+++ b/lib/lightning_web/live/ai_assistant/modes/job_code.ex
@@ -40,6 +40,13 @@ defmodule LightningWeb.Live.AiAssistant.Modes.JobCode do
     def changeset(params) do
       %__MODULE__{}
       |> cast(params, [:content])
+      |> validate_required([:content],
+        message: "Please enter a message before sending"
+      )
+      |> validate_length(:content,
+        min: 1,
+        message: "Please enter a message before sending"
+      )
       |> cast_embed(:options, with: &options_changeset/2)
     end
 
diff --git a/test/lightning_web/live/ai_assistant_live_test.exs b/test/lightning_web/live/ai_assistant_live_test.exs
index 02bedff390..1fec4578b2 100644
--- a/test/lightning_web/live/ai_assistant_live_test.exs
+++ b/test/lightning_web/live/ai_assistant_live_test.exs
@@ -308,7 +308,8 @@ defmodule LightningWeb.AiAssistantLiveTest do
         assert has_element?(input_element)
         refute render(input_element) =~ "disabled=\"disabled\""
         assert has_element?(submit_btn)
-        refute render(submit_btn) =~ "disabled=\"disabled\""
+        # Submit button should be disabled when no content is entered
+        assert render(submit_btn) =~ "disabled=\"disabled\""
 
         html =
           view
@@ -2354,7 +2355,8 @@ defmodule LightningWeb.AiAssistantLiveTest do
         )
 
       refute render(input_element) =~ "disabled=\"disabled\""
-      refute render(submit_btn) =~ "disabled=\"disabled\""
+      # Submit button should be disabled when no content is entered
+      assert render(submit_btn) =~ "disabled=\"disabled\""
 
       refute render(input_element) =~ "Save your workflow first"
     end
diff --git a/test/lightning_web/live/workflow_live/ai_assistant_component_test.exs b/test/lightning_web/live/workflow_live/ai_assistant_component_test.exs
index 36d0aed528..9d0f654443 100644
--- a/test/lightning_web/live/workflow_live/ai_assistant_component_test.exs
+++ b/test/lightning_web/live/workflow_live/ai_assistant_component_test.exs
@@ -289,4 +289,45 @@ defmodule LightningWeb.WorkflowLive.AiAssistant.ComponentTest do
              ]
     end
   end
+
+  describe "form validation" do
+    alias LightningWeb.Live.AiAssistant.Modes.WorkflowTemplate
+
+    test "JobCode Form validates empty content" do
+      changeset = JobCode.Form.changeset(%{"content" => ""})
+
+      assert changeset.valid? == false
+      assert Keyword.has_key?(changeset.errors, :content)
+      {msg, _opts} = changeset.errors[:content]
+      assert msg == "Please enter a message before sending"
+    end
+
+    test "JobCode validate_form includes content validation" do
+      changeset = JobCode.validate_form(%{"content" => nil})
+
+      assert changeset.valid? == false
+      assert Keyword.has_key?(changeset.errors, :content)
+    end
+
+    test "WorkflowTemplate DefaultForm validates empty content" do
+      changeset = WorkflowTemplate.DefaultForm.changeset(%{"content" => ""})
+
+      assert changeset.valid? == false
+      assert Keyword.has_key?(changeset.errors, :content)
+      {msg, _opts} = changeset.errors[:content]
+      assert msg == "Please enter a message before sending"
+    end
+
+    test "form validation accepts valid content" do
+      # JobCode
+      changeset = JobCode.validate_form(%{"content" => "Help me with my code"})
+      assert changeset.valid? == true
+
+      # WorkflowTemplate
+      changeset =
+        WorkflowTemplate.validate_form(%{"content" => "Create a workflow"})
+
+      assert changeset.valid? == true
+    end
+  end
 end