# Missing variable value when checkpointing enabled

When I add the line

adj_

to my time-dependent optimization code, which works fine without checkpointing, I get

...

====== Revolve: Replay from equation 64 (first equation of timestep 9) to equation 70 (last equation of timestep 9). ======

Revolve: No need to replay equation 64.

Revolve: Checkpoint equation 64 in memory.

Revolve: No need to replay equation 65.

Revolve: No need to replay equation 66.

Revolve: No need to replay equation 67.

Revolve: No need to replay equation 68.

Revolve: No need to replay equation 69.

Revolve: No need to replay equation 70.

Revolve: Solving adjoint equation 70.

Warning: got zero RHS for the solve associated with variable u0:9:0:

Revolve: Solving adjoint equation 69.

Solving linear system of size 1111 x 1111 (PETSc Krylov solver).

Revolve: Solving adjoint equation 68.

Solving linear system of size 8442 x 8442 (PETSc Krylov solver).

Revolve: Solving adjoint equation 67.

Revolve: Solving adjoint equation 66.

Revolve: Solving adjoint equation 65.

Revolve: Solving adjoint equation 64.

Revolve: Delete checkpoint equation 64.

====== Revolve: Replay from equation 50 (first equation of timestep 7) to equation 56 (last equation of timestep 7) =======

Revolve: Replaying equation 50.

Revolve: Replaying equation 51.

Revolve: Replaying equation 52.

Revolve: Replaying equation 53.

Revolve: Replaying equation 54.

Traceback (most recent call last):

...

libadjoint.

After this I see checkpoints for u0:0 through u0:5 but no u0:6 on disk:

martinal@...$ ls u0\:*

u0:0:1:Forward.xml u0:1:0:Forward.xml u0:2:0:Forward.xml u0:3:0:Forward.xml u0:4:0:Forward.xml u0:5:0:Forward.xml

Do I need to set snaps_on_disk and snaps_in_ram differently?

I'm sort of expecting dolfin-adjoint to pick up invalid parameters

as it has been pretty good at that so far :)

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- Solved by:
- Martin Sandve Alnæs

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