--- a/browser/components/sessionstore/SessionCookies.jsm
+++ b/browser/components/sessionstore/SessionCookies.jsm
@@ -52,20 +52,30 @@ var SessionCookiesInternal = {
       let expiry = "expiry" in cookie ? cookie.expiry : MAX_EXPIRY;
       let cookieObj = {
         host: cookie.host,
         path: cookie.path || "",
         name: cookie.name || ""
       };
 
       let originAttributes = cookie.originAttributes || {};
-      if (!Services.cookies.cookieExists(cookieObj, originAttributes)) {
-        Services.cookies.add(cookie.host, cookie.path || "", cookie.name || "",
-                             cookie.value, !!cookie.secure, !!cookie.httponly,
-                             /* isSession = */ true, expiry, originAttributes);
+      let exists = false;
+      try {
+        exists = Services.cookies.cookieExists(cookieObj, originAttributes);
+      } catch (ex) {
+        Cu.reportError(`nsCookieService::CookieExists failed with error '${ex}' for '${JSON.stringify(cookie)}'.`);
+      }
+      if (!exists) {
+        try {
+          Services.cookies.add(cookie.host, cookie.path || "", cookie.name || "",
+                               cookie.value, !!cookie.secure, !!cookie.httponly,
+                               /* isSession = */ true, expiry, originAttributes);
+        } catch (ex) {
+          Cu.reportError(`nsCookieService::Add failed with error '${ex}' for cookie ${JSON.stringify(cookie)}.`);
+        }
       }
     }
   },
 
   /**
    * Handles observers notifications that are sent whenever cookies are added,
    * changed, or removed. Ensures that the storage is updated accordingly.
    */