frantejo
Hey thanks for sending that through. I'll document how I debugged it for posterity.
So firstly, I opened your scene and saw that it was saved on frame 33, while the solver start frame is set to -10. That won't necessarily break the scene in itself, but for authoring characters we advise that all authoring happens on the solver start frame.
When I reset the timeline, I still saw the same error. To get more detailed output from the script editor, you can change the Ziva verbosity level. If you run this in a mel editor:
ziva -vb 4
You will get more information.
So now if I try to step forward one frame, I can see this:
// Error: ziva 2017-11-22 14:38:55.206 ERR| zGeoNode zGeo201 - mesh failed basic quality checks: -nonmanifoldVertices //
// Error: ziva 2017-11-22 14:38:55.207 ERR| Failed to prepare GeoData cache in zGeo201 //
// Error: ziva 2017-11-22 14:38:55.208 ERR| Could not compute GeoNode `zGeo201'. //
// Error: ziva 2017-11-22 14:38:55.318 ERR| zGeo251.iNeutralMatrix has null value. It's probably not connected, but it must be. //
// Error: ziva 2017-11-22 14:38:55.319 ERR| Could not compute GeoNode `zGeo251'. //
// Error: ziva 2017-11-22 14:38:55.361 ERR| GeoData: zBone node is null //
// Error: ziva 2017-11-22 14:38:55.420 ERR| GeoData: zTissue node is null //
// Error: ziva 2017-11-22 14:38:55.504 ERR| zFiber:zFiber33 cannot compute because iGeo //
// Error: ziva 2017-11-22 14:38:55.506 ERR| zFiber:zFiber33 cannot compute because iGeo //
So starting at the top, if I find zGeo201 and graph it's connections in the node editor..

I can see that it's connected to the spine_skellShape. The first error tells me that there is a problem with non-manifold vertices. if I select that mesh and run
zMeshCheck;
it tells me which vertices are troublesome.
// Error: |skeleton_grp|spine_skell failed checks: -nonmanifoldVertices //
// Result: |skeleton_grp|spine_skell.vtx[217] |skeleton_grp|spine_skell.vtx[410] //

Using the Ziva menu I just deleted that mesh to see if I could get the scene to a solveable state. I still have this error:
// Error: ziva 2017-11-22 14:49:17.914 ERR| zGeo251.iNeutralMatrix has null value. It's probably not connected, but it must be. //
// Error: ziva 2017-11-22 14:49:17.916 ERR| Could not compute GeoNode `zGeo251'. //
// Error: ziva 2017-11-22 14:49:17.958 ERR| GeoData: zTissue node is null //
// Error: ziva 2017-11-22 14:49:18.012 ERR| zFiber:zFiber33 cannot compute because iGeo //
// Error: ziva 2017-11-22 14:49:18.014 ERR| zFiber:zFiber33 cannot compute because iGeo //
// Error: ziva 2017-11-22 14:49:18.016 ERR| Attachment input to zSolver is not a geo data //
If I graph the zGeo251 connections, I can see it doesn't have a corresponding mesh.

Seeing as it's an "orphan" zGeo node, I'm going to delete it, and the corresponding zAttachments and zTissue because those won't make sense without geometry. I'm NOT deleting the embedder because that's used by everything.
That's it. The scene now solves.