We were recently notified by a SPEDAS user that there was a problem with the SPEDAS 4.0 interface to the GEOPACK library. Specifically, the field line tracing routines were crashing if the TS07 field model was selected.
We have corrected the issue, and built a new release, SPEDAS 4.1, containing the updated code. This is the only difference from the previous SPEDAS 4.0 release. W.e recommend that SPEDAS 4.0 users update as soon as possible to SPEDAS 4.1. The IDL source code, and compiled Virtual Machine executables, are available from the SPEDAS Downloads and Installation page.