# Trouble updating from 4.9 to 4.15
**URL:** https://community.freefem.org/t/trouble-updating-from-4-9-to-4-15/3877
**Category:** General Discussion
**Created:** [April 22, 2025, 10:05pm UTC](https://community.freefem.org/t/trouble-updating-from-4-9-to-4-15/3877 "2025-04-22T22:05:50Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@bpabbott](https://community.freefem.org/u/bpabbott)
#### Post date: [April 22, 2025, 10:05pm UTC](https://community.freefem.org/t/trouble-updating-from-4-9-to-4-15/3877/1 "2025-04-22T22:05:50Z")
## I’m quite novice at FreeFEM. I’ve been using edp-files we put together several years back (v9). While upgrading the a new computer I discovered that one of the edp-files throws an error in v15. I’ve included some of the code below.
## … fespace Vh(MYmesh, [P2, P2, P2, P2], periodic = [[-2, y], [-4, y]]); … Vh [f, u, v, w], [ff, uu, vv, ww]; … Mat A(Vh.ndof); Mat B(Vh.ndof);
The error occurs for [Mat A(Vh.ndof);]
165 : Mat The Identifier Mat does not exist
Error line number 165, in file .\myfile.edp, before token Mat
I’m hoping this is due to the need to load a package, or something equally simple.
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### Author:  [@bpabbott](https://community.freefem.org/u/bpabbott)
#### Post date: [April 22, 2025, 10:54pm UTC](https://community.freefem.org/t/trouble-updating-from-4-9-to-4-15/3877/2 "2025-04-22T22:54:18Z")
I found the problem … SLEPc-complex has been superseded by PETSc-complex
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### Author:  [@prj](https://community.freefem.org/u/prj)
#### Post date: [April 23, 2025, 6:39am UTC](https://community.freefem.org/t/trouble-updating-from-4-9-to-4-15/3877/3 "2025-04-23T06:39:56Z")
Indeed, the `load "SLEPc"` and `load "SLEPc-complex"` are now “useless” in the sense that they do nothing but print that you need to load `PETSc` or `PETSc-complex` instead.