diff --git a/rust/agama-server/tests/server_service.rs b/rust/agama-server/tests/server_service.rs
index 7367da7972..324f3c6b7e 100644
--- a/rust/agama-server/tests/server_service.rs
+++ b/rust/agama-server/tests/server_service.rs
@@ -194,7 +194,18 @@ async fn test_put_config_without_mode(ctx: &mut Context) -> Result<(), Box<dyn E
         .unwrap();
 
     let response = ctx.client.send_request(request).await;
-    assert_eq!(response.status(), StatusCode::BAD_REQUEST);
+    assert_eq!(response.status(), StatusCode::OK);
+
+    let request = Request::builder()
+        .uri("/extended_config")
+        .body("".to_string())
+        .unwrap();
+
+    let response = ctx.client.send_request(request).await;
+    assert_eq!(response.status(), StatusCode::OK);
+
+    let body = body_to_string(response.into_body()).await;
+    assert!(body.contains(r#""product":{"id":"SLES","mode":"standard"}"#));
 
     Ok(())
 }
@@ -259,7 +270,6 @@ async fn test_patch_config_success(ctx: &mut Context) -> Result<(), Box<dyn Erro
 
     let body = body_to_string(response.into_body()).await;
     assert!(body.contains(r#""l10n":{"keymap":"en"}"#));
-    dbg!(&body);
     assert!(body.contains(r#""product":{"id":"SLES","mode":"standard"}"#));
 
     Ok(())
diff --git a/rust/agama-software/src/service.rs b/rust/agama-software/src/service.rs
index b757b02b25..57dd7af149 100644
--- a/rust/agama-software/src/service.rs
+++ b/rust/agama-software/src/service.rs
@@ -294,6 +294,26 @@ impl Service {
             .map(|url| Url::parse(&url).ok())
             .flatten();
     }
+
+    /// Completes the configuration with the product mode if it is missing.
+    ///
+    /// Agama uses the first available mode (if any) in case the user does not set one.
+    async fn add_product_mode(&mut self, config: &mut Config) {
+        let Some(product_config) = &mut config.product else {
+            return;
+        };
+
+        if product_config.mode.is_some() {
+            return;
+        }
+
+        let Some(selected_product) = &self.product else {
+            return;
+        };
+
+        let selected_product = selected_product.read().await;
+        product_config.mode = selected_product.mode.clone();
+    }
 }
 
 impl Actor for Service {
@@ -323,6 +343,7 @@ impl MessageHandler<message::SetConfig<Config>> for Service {
 
         let mut config = message.config.clone().unwrap_or_default();
         self.add_kernel_cmdline_defaults(&mut config);
+        self.add_product_mode(&mut config).await;
 
         {
             let mut state = self.state.write().await;
diff --git a/rust/agama-utils/src/products.rs b/rust/agama-utils/src/products.rs
index 4ff1a33a7e..6bcb05a045 100644
--- a/rust/agama-utils/src/products.rs
+++ b/rust/agama-utils/src/products.rs
@@ -63,8 +63,6 @@ pub enum Error {
     UnknownProduct(String),
     #[error("Invalid mode '{1}' for product '{0}'")]
     UnknownMode(String, String),
-    #[error("Mode required for product '{0}'")]
-    ModeRequired(String),
 }
 
 /// Products registry.
@@ -139,12 +137,15 @@ impl Registry {
     /// * `id`: product ID.
     /// * `mode`: product mode. Required only if the product has modes.
     pub fn find(&self, id: &str, mode: Option<&str>) -> Result<ProductSpec, Error> {
+        let mut mode = mode.clone();
         let Some(template) = self.products.iter().find(|p| p.id == id) else {
             return Err(Error::UnknownProduct(id.to_string()));
         };
 
-        if template.has_modes() && mode.is_none() {
-            return Err(Error::ModeRequired(id.to_string()));
+        if mode.is_none() {
+            if let Some(default_mode) = template.modes.first() {
+                mode = Some(default_mode.id.as_str());
+            }
         }
 
         template.to_product_spec(mode)
@@ -539,9 +540,10 @@ mod test {
 
     #[test_context(Context)]
     #[test]
-    fn test_find_product_with_required_mode(ctx: &mut Context) {
-        let product = ctx.registry.find("SLES", None).unwrap_err();
-        assert!(matches!(product, Error::ModeRequired(_)));
+    fn test_find_product_without_mode(ctx: &mut Context) {
+        let product = ctx.registry.find("SLES", None).unwrap();
+        assert_eq!(&product.id, "SLES");
+        assert_eq!(&product.mode.unwrap(), "standard");
     }
 
     #[test_context(Context)]
diff --git a/rust/package/agama.changes b/rust/package/agama.changes
index 156317def4..e6171c94bf 100644
--- a/rust/package/agama.changes
+++ b/rust/package/agama.changes
@@ -1,4 +1,9 @@
+-------------------------------------------------------------------
+Wed Jan 28 16:14:52 UTC 2026 - Imobach Gonzalez Sosa <igonzalezsosa@suse.com>
+
+- Use the first product mode if none is given (related to jsc#PED-14307).
 
+-------------------------------------------------------------------
 Wed Jan 28 12:59:50 UTC 2026 - José Iván López González <jlopez@suse.com>
 
 - Add agama-iscsi service and integrate iSCSI into the new HTTP API