I've resided in a foreign country whole 2020 and at the time of filing. At principal residence info, I left county field blank "No Entry" but didn't go through by error.

Are you filing a resident or nonresident California income tax return? The county field will not come up if you are filing a nonresident return.

In My Info in the federal section, your resident state should be Foreign or U.S. Possession. At the bottom, Other state income is California.

Thank you very much. You are right. My resident state is foreign or US possession.  I could file as nonresident CA.

Are you a legal resident of this foreign country, i.e. have that country's equivalent of a U.S. green card? Are you still registered to vote in CA or hold a CA driver's license?