Yes.

I understood the cause of the error. When you do as instructed
"If you already start mining, just click Stop mining" the wallet is blocked. Stop mining is not necessary and then the command "dumpprivkey and paste in the address and hit ENTER" it works correctly, because mining unlocks the wallet file.

I think need to correct a little manual.

Who helps, many thanks for the support.

And, how to switch number of threads to use in zettelkasten.conf (use zettelkastend demon)?


upd:

./zettelkastend -genproclimit=3 - run on 3 threads

or

...
genproclimit=3
...

in zettelkasten.conf