It's the same as the title, and when I checked the log, there were hundreds to thousands of lines with the following content.
The larger the page index of the Pdf from which you select letters, the more logs will be recorded.
.notdef: no mapping.
.notdef: no mapping.
.notdef: no mapping.
.notdef: no mapping.
.notdef: no mapping.
.notdef: no mapping.
.
.
.
can't create CMap Adobe-KR1-UCS2'. can't create CMap Adobe-KR1-UCS2'.
can't create CMap Adobe-KR1-UCS2'. can't create CMap Adobe-KR1-UCS2'.
can't create CMap Adobe-KR1-UCS2'. can't create CMap Adobe-Identity-UCS2'.
can't create CMap Adobe-KR1-UCS2'. can't create CMap Adobe-KR1-UCS2'.
can't create CMap Adobe-Identity-UCS2'. can't create CMap Adobe-Identity-UCS2'.
can't create CMap `Adobe-Identity-UCS2'.
I don't know why this is happening. Is there a solution?