Legal Question in Civil Litigation in California

Judges, if not the law, tend to be rather practical. As you knew about the demurrer response, I would recommend that you respond but point out to the court that you were not served at the proper address. The judge will probably not dismiss the defendant's pleading but he/she will not be very happy with them. What you need to understand is this: the law abhors a vacuum which in plain English means that if there are two parties, the law prefers that both sides be heard before a decision is made.

If you know a demurrer has been filed and you fail to oppose that demurrer in writing before the hearing, you run the very real risk that the demurrer will be granted. Judges generally will not "dismiss" demurrers at the time of their hearing.

Discretion being the better part of valor, you should definitely respond to the demurrer.

After all, the judge may reject your argument that you were not properly served, note that the demurrer was unopposed, grant it, and dismiss your case.

If it was wrong because your official address was incorrect, you should not fail to oppose the demurrer. You can just put this as one more reason to deny the demurrer. You could bring an ex parte motion to strike the demurrer, but Judges are not likely to grant that. If you do not have time to respond because of the wrong service address, then you can ask the opposing party to move the hearing so you have more time.

Unless the demurrer is totally without merit, cut to the chase and just file an amended complaint.