ApplyChanges returns Bad_InvalidState if any TrustLIst is still open for writing. No changes were be applied and ApplyChanges can be called again after the TrustList is closed.

If a Session is closed or abandoned then the transaction is closed and all pending changes are discarded.

If ApplyChanges is called and there is no active transaction then the Server returns Bad_NothingToDo. If there is an active transaction, however, no changes are pending the result is Good and the transaction is closed.

When a Server Certificate or TrustList changes active SecureChannels are not immediately affected. This ensures the caller of ApplyChanges can get a response to the Method call. Once the Method response is returned the Server shall force existing SecureChannels affected by the changes to renegotiate and use the new Server Certificate and/or TrustLists.

Servers may close SecureChannels without discarding any Sessions or Subscriptions. This will seem like a network interruption from the perspective of the Client and the Client reconnect logic (see OPC 10000-4) allows them to recover their Session and Subscriptions. Note that some Clients may not be able to reconnect because they are no longer trusted.

Other Servers may need to do a complete shutdown. In these cases, the Server shall advertise its intent to interrupt connections by setting the SecondsTillShutdown and ShutdownReason Properties in the ServerStatus Variable.

If a TrustList change only affects UserIdentity associated with a Session then Servers shall re-evaluate the UserIdentity and if it is no longer valid the Session and associated Subscriptions are closed.

This Method shall be called from an authenticated SecureChannel and from the Session that created the transaction and has access to the SecurityAdmin Role (see 7.2).



Method Result Codes (defined in Call Service)

Result Code



The current user does not have the rights required.

Table 67 specifies the AddressSpace representation for the ApplyChanges Method.

Table 67 – ApplyChanges Method AddressSpace Definition