File-Upload: Unvalid MIME-Typ

[julius-low-kernel]

Hey there,
I’m building my first Custom-Code project.
I need to upload a CSV in my Formmodel, but it can’t find the MIME-Type.

My Formodel (I get the same Error without specification):

My Preview App:

CSV content:

Can someone tell my what I am doing wrong?

[gildardo-cached-canyon]

Hi @julius-low-kernel,
the A12 version 2026.06 is not released yet, that’s why I tried your case in the preview app version 2025.06-ext5 with the basic workspace uploading a csv file as attachment, but I couldn’t reproduce it (I could save the document), for that reason, I have the following questions:

1. Which installer did you use?
2. If you are implementing a Custom-Code project, why aren’t you using the Project Template (PT)? In the PT, you can configure the allowed mime types (server-side) in the file ‘server/app/src/main/resources/config/application-shared.properties’ with the property ‘mgmtp.a12.template.server.attachment.allowedMimeTypes’ (normally already present in the PT).

[julius-low-kernel]

Hey Gildardo,
I was using the Installer from GetA12.com and got the 25.06-ext5.

I’m using the PT, but the community edition, with my mgm credentials for artifactory, since I did not find an enterprise version of the PT.

The allowedMimeTypes was indeed set to image/jpeg, but after replacing it with text/csv,application/vnd.ms-excel,application/octet-stream, it still did not work.

I’ve tested deleting the MIME-Typ-Attachment-Upload-Constraint in my SME Formmodel and set both properMimeType and trustExternalMimeType to false, so that every Attachment-Upload should be accepted. I also tried to set the allowedMimeType to “* / *”, to get a Wildcard, but that did not help as well.

Is there anything I could have messed up, while setting up the PT?