diff --git a/app/api/groups/route.ts b/app/api/groups/route.ts
index 1b3c887..f6377c3 100644
--- a/app/api/groups/route.ts
+++ b/app/api/groups/route.ts
@@ -207,11 +207,25 @@ export async function POST(req: Request) {
       // Try to get error details from Keycloak
       let errorMessage = 'Échec de la création du groupe';
       try {
-        const errorData = await response.json();
-        // Keycloak error format: { errorMessage: "..." } or { error: "..." }
-        errorMessage = errorData.errorMessage || errorData.error || errorData.message || errorMessage;
-      } catch {
-        // If response is not JSON, use status text
+        // Read response as text first (can only read body once)
+        const text = await response.text();
+        
+        if (text.trim()) {
+          // Try to parse as JSON
+          try {
+            const errorData = JSON.parse(text);
+            // Keycloak error format: { errorMessage: "..." } or { error: "..." }
+            errorMessage = errorData.errorMessage || errorData.error || errorData.message || errorMessage;
+          } catch {
+            // If not JSON, use the text as error message
+            errorMessage = text;
+          }
+        } else {
+          // Empty response, use status text
+          errorMessage = response.statusText || errorMessage;
+        }
+      } catch (readError) {
+        // If reading response fails, use status text
         errorMessage = response.statusText || errorMessage;
       }
       
diff --git a/app/missions/equipe/page.tsx b/app/missions/equipe/page.tsx
index 71ba6cd..3580b43 100644
--- a/app/missions/equipe/page.tsx
+++ b/app/missions/equipe/page.tsx
@@ -495,10 +495,24 @@ export default function EquipePage() {
         // Try to parse error message from response
         let errorMessage = "Échec de la création du groupe";
         try {
-          const errorData = await response.json();
-          errorMessage = errorData.message || errorData.error || errorMessage;
-        } catch {
-          // If response is not JSON, use status text
+          // Read response as text first (can only read body once)
+          const text = await response.text();
+          
+          if (text.trim()) {
+            // Try to parse as JSON
+            try {
+              const errorData = JSON.parse(text);
+              errorMessage = errorData.message || errorData.error || errorMessage;
+            } catch {
+              // If not JSON, use the text as error message
+              errorMessage = text;
+            }
+          } else {
+            // Empty response, use status text
+            errorMessage = response.statusText || errorMessage;
+          }
+        } catch (readError) {
+          // If reading response fails, use status text
           errorMessage = response.statusText || errorMessage;
         }
         throw new Error(errorMessage);