Hi Nadia,
My only idea is that maybe you are using a super-old version of ChimeraX?  This option was added in February 2023 and is available in version 1.6 and later, as per the Change Log:
<https://www.rbvi.ucsf.edu/trac/ChimeraX/wiki/ChangeLog>

Besides the "open" command with "format swissdock" you could also try using the File->Open dialog from the main menu and choosing file type "SwissDock" as described in the Change Log entry for Feb 3 2023 (link above).

I hope this helps,
Elaine
-----
Elaine C. Meng, Ph.D.                       
UCSF Chimera(X) team
Resource for Biocomputing, Visualization, and Informatics
Department of Pharmaceutical Chemistry
University of California, San Francisco


> On Apr 11, 2025, at 11:30 AM, Nadia Elghobashi-Meinhardt via ChimeraX-users <chimerax-users@cgl.ucsf.edu> wrote:
>
> Dear all,
>
> When I try to open a SwissDock .dock4 file in ChimeraX, the swissdock format is not recognized.
> The chimeraX forum advises using "format swissdock" when opening the file, but I am getting 'invalid "format" argument'.
>
> Does anybody have a solution to this problem?
>
> Many thanks,
> Nadia