I am currently using AceFEM version 7.303 and Mathematica 12.2 but had the same problem with other versions before. My laptop as well as the server I use work with Linux.
When I run the example "MIEL modeling of 2D uniformly distributed micro-structure" from the documentation but enforce many small load steps (for example 1000 steps) at the macro scale, the simulation does not finish. Everything works perfectly fine until the following error occurs.
The load step when the error occurs is always the same on the same machine but is different for my laptop compared to the server. I thought that the problem could be about reaching some machine limits in file handling which leads to failing the restart of the micro problem but I did not succeed in circumventing the error.
It would be great if anyone could help.