An error occurred when SQL Server exported the flat file: The code page on Destination-3_txt. Inputs[flat File Destination Input]. Columns[userid] is 936 and was required to be 1252.

When I export a flat file:
Error 0xc00470d4:data Flow Task 1:the code page on Destination-3_txt. Inputs[flat File Destination Input]. Columns[userid] is 936 and was required to be 1252.
(SQL Server Import and Export Wizard)
Sometimes it can be verified through, sometimes not, what is the reason?

I tried to use Unicode encoding (sometimes I can), not with 1251 (Ansi-latin l)

Workaround:

Change the code page to the corresponding 936 encoding to

View the encoded statement in SQL:

SELECT collationproperty (' Chinese_prc_stroke_ci_ai_ks_ws ', ' CodePage ')

An error occurred when SQL Server exported the flat file: The code page on Destination-3_txt. Inputs[flat File Destination Input]. Columns[userid] is 936 and was required to be 1252.