--- a/mailnews/base/src/nsMsgAccount.cpp
+++ b/mailnews/base/src/nsMsgAccount.cpp
@@ -427,10 +427,10 @@ nsMsgAccount::ToString(nsAString& aResul
 }
 
 NS_IMETHODIMP
 nsMsgAccount::ClearAllValues()
 {
   nsresult rv = getPrefService();
   NS_ENSURE_SUCCESS(rv, rv);
 
-  return m_prefs->DeleteBranch(nullptr);
+  return m_prefs->DeleteBranch("");
 }

--- a/mailnews/base/src/nsMsgAccountManager.cpp
+++ b/mailnews/base/src/nsMsgAccountManager.cpp
@@ -707,17 +707,21 @@ nsMsgAccountManager::RemoveAccount(nsIMs
         }
       }
       // clear out all identity information if no other account uses it.
       if (!identityStillUsed)
         identity->ClearAllValues();
     }
   }
 
-  aAccount->ClearAllValues();
+  // It is not a critical problem if this fails as the account was already
+  // removed from the list of accounts so should not ever be referenced.
+  // Just print it out for debugging.
+  rv = aAccount->ClearAllValues();
+  NS_ASSERTION(NS_SUCCEEDED(rv), "removing of account prefs failed");
   return NS_OK;
 }
 
 nsresult
 nsMsgAccountManager::OutputAccountsPref()
 {
   nsCString accountKey;
   mAccountKeyList.Truncate();