diff --git a/cloud_backend/routers/manager_auth.py b/cloud_backend/routers/manager_auth.py
index 435c77c..aad8fb0 100644
--- a/cloud_backend/routers/manager_auth.py
+++ b/cloud_backend/routers/manager_auth.py
@@ -59,7 +59,7 @@ def register_manager(
     _admin=Depends(get_current_admin),
 ):
     existing = db.query(ManagerAccount).filter(ManagerAccount.email == body.email).first()
-    sites = db.query(Site).filter(Site.id.in_(body.site_ids)).all()
+    sites = db.query(Site).filter(Site.site_id.in_(body.site_ids)).all()
 
     if existing:
         # Email already exists — just add the new site access links, don't recreate the account
@@ -114,11 +114,11 @@ class ManagerBySiteOut(BaseModel):
 
 @router.get("/by-site/{site_id}", response_model=list[ManagerBySiteOut])
 def get_managers_by_site(
-    site_id: int,
+    site_id: str,
     db: Session = Depends(get_db),
     _admin=Depends(get_current_admin),
 ):
-    site = db.query(Site).filter(Site.id == site_id).first()
+    site = db.query(Site).filter(Site.site_id == site_id).first()
     if not site:
         raise HTTPException(status_code=404, detail="Site not found")
     return site.manager_accounts
@@ -128,7 +128,7 @@ def get_managers_by_site(
 
 class SiteAccessRemoveRequest(BaseModel):
     manager_id: int
-    site_id: int
+    site_id: str  # site_id UUID string, not integer PK
 
 
 @router.delete("/site-access", status_code=status.HTTP_204_NO_CONTENT)
@@ -141,7 +141,7 @@ def remove_manager_site_access(
     if not manager:
         raise HTTPException(status_code=404, detail="Manager not found")
 
-    site = db.query(Site).filter(Site.id == body.site_id).first()
+    site = db.query(Site).filter(Site.site_id == body.site_id).first()
     if not site:
         raise HTTPException(status_code=404, detail="Site not found")
 
diff --git a/cloud_backend/schemas/manager.py b/cloud_backend/schemas/manager.py
index 8946e1e..1b681cd 100644
--- a/cloud_backend/schemas/manager.py
+++ b/cloud_backend/schemas/manager.py
@@ -8,7 +8,7 @@ class ManagerRegisterRequest(BaseModel):
     email: str
     password: str
     full_name: Optional[str] = None
-    site_ids: list[int] = []
+    site_ids: list[str] = []  # site_id UUID strings, not integer PKs
 
 
 class ManagerLoginRequest(BaseModel):
diff --git a/sysadmin_panel/src/pages/SiteDetailPage.jsx b/sysadmin_panel/src/pages/SiteDetailPage.jsx
index 15ca751..ede7166 100644
--- a/sysadmin_panel/src/pages/SiteDetailPage.jsx
+++ b/sysadmin_panel/src/pages/SiteDetailPage.jsx
@@ -75,7 +75,7 @@ export default function SiteDetailPage() {
     if (!newMgrEmail.trim() || !newMgrPass.trim()) return
     setAddingMgr(true)
     try {
-      await addManagerToSite(newMgrEmail.trim(), newMgrName.trim(), newMgrPass.trim(), Number(siteId))
+      await addManagerToSite(newMgrEmail.trim(), newMgrName.trim(), newMgrPass.trim(), siteId)
       toast.success('Manager added')
       setModal(null)
       setNewMgrEmail(''); setNewMgrName(''); setNewMgrPass('')
@@ -90,7 +90,7 @@ export default function SiteDetailPage() {
   async function doRemoveManager(managerId) {
     setRemovingMgrId(managerId)
     try {
-      await removeManagerSiteAccess(managerId, Number(siteId))
+      await removeManagerSiteAccess(managerId, siteId)
       toast.success('Access removed')
       setManagers(prev => prev.filter(m => m.id !== managerId))
     } catch (e) {