SharePoint Online and the curse of the .stp file extension


This blog post is for anyone who hits a similar issue that we had with a customer a few weeks ago. We have built a solution for a innovative renewable electrics research organization to help them manage their manufacturing release process.

The solution is built on SharePoint Online with workflow features provided by Logic Apps, Power Apps and Angular to provide a customized user interface.

Recently, we had a support call where they were having problems with an engineering file which had a file extension of .stp

My mind went racing back to old SharePoint file formats and I remember exporting list templates with an .stp file format.

Immediately I wondered if this must be the issue the fact that SharePoint is processing these files as SharePoint templates.


Manage list templates – SharePoint (

So the behaviour we experienced was this, part of the solution copies content from one library to another. The content has metadata associated but that metadata was not being copied over.

To rule out native SharePoint function, I decided to try copying over the file using the out of the box Move function when in a SharePoint Document Library. Funnily enough the same behaviour occurred, and the file was moved but without any metadata. I was a little bit relieved as at least it wasn’t just our code!

I raised a call with Microsoft, and we went through the process of showing the Microsoft support team what was happening, and the same thing happened for them. They asked us to try do the same thing but this time via the classic experience. When the file was moved using classic experience it worked correctly.

We left Microsoft to do some more investigation.


Whilst that was in place I did some more digging into the .stp file format for the engineering software. These .stp files are STEP files and they can be .stp or .step file. We spoke with the customer and suggested that they try using .step as the file extension as a workaround. This resolved the problem for the solution and SharePoint behaved as it should.

So for the time being the workaround is to use .step rather than .stp file extensions whilst we try out some alternative approaches with document library custom templates.

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