Hello,
This bug is related to this one which is corrected :
Fixed issue # 8638

I put a video of all the steps to reproduce the bug.
When exporting an anonymous questionnaire responses and answers that is not complete , then the response date ( timestamp) take NULL.

When importing these responses, LimeSurvey plant because it does not replace the NULL value with 0.
This is due to PostgreSQL , MySQL replaces good 0.

error messages are not specific enough.

I added the files to reproduce these errors:
limesurvey_survey_88379.csv
vvexport_88379.csv

A third file is present:
vvexport_numeric_and_spaces.csv

I do not have the questionnaire available immediately. But the worry is that when a question is numeric type and the response contains a space instead of a digit ( response not captured by the respondent) , import plant also .

Here is the error message:

CDbCommand failed to execute the SQL statement : SQLSTATE [ 22P02 ] : Invalid text representation : 7 ERROR: invalid input syntax for type numeric : " "
LINE 1 : ... 321 " ) VALUES ( 10101 , '1980 -01-01 0:00:00 ',' en ','' ,'', '' ...

It is in this column :
Your department administrative assignment :

In line 4 , after fr, there is nothing.

Mysql bug for me, but a friend to a higher version and the value is replaced by 0

For information, here is the info on the vv file (which I can not provide in its entirety) :
( 12314 responses to the questionnaire ( 11137 complete responses , partial responses in 1177 )

I did the test with complete answers , following the above-mentioned problem .