# Mesh too coarse for the GAMG solver:¶

Error

**Solver error: The mesh on some computing core is too coarse for the GAMG solver.**

## What happened?¶

The GAMG solver (which was selected for one or more variables) could not find enough cells to use at its lowest level. For more information on the GAMG solver, please refer to this page.

## What could be the possible reason?¶

There could be three reasons for this error to occur:

1- The mesh is too coarse: this normally occurs if, per computing core, the number of 3D elements in your mesh is very low (for instance, under 1000). This can be checked under “Domain” - “Mesh” in your simulation settings.

2- The number of computing cores is too high for the mesh: the ideal number of 3D elements per core is recommended to be in the range of 100000 to 250000.

3- The number of cells in the coarsest level for GAMG is too high: this setting can be found under the parameters for the GAMG solver. The default value for this parameter is 10.

## What can I do now?¶

1- If your mesh has more than 1000 3D elements, but if the number of 3D elements per computing core is less than the recommended range, try using a smaller number of cores.

2- If your mesh has less than 1000 3D elements, and you are already using the lowest number of computing cores (i.e. 1), please either decrease the number of cells in coarsest level for the GAMG solver, or use a finer mesh. Note, that using a very small number of cells in coarsest level for the GAMG solver might reduce the quality of the solution.

3- If you do not have the option of changing the mesh fineness, and if the solution is not suitable with a lower number of coarsest level cells for GAMG, please use a different solver.

Note

If the above suggestions did not solve your problem, then please post the issue on our forum or contact us.