Conversion from drawing to DXF

Hello

We just migrated from SW 2014 to 2018 in September.

Since then, when saving a drawing file in DXF, some lines appear dashed in Autocad.

Do you have this problem?

Thank you

I didn't have the opportunity to test. But there are conversion options (using layers/associating a stroke type) to configure.
Ideally, you should still have a machine with SW14 to compare the export parameters.

The problem is that the whole park has migrated...

I've looked at the conversion options, and I don't see what could have changed