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Error e0400b: Cannot open project. Invalid Format

I created a project using images from 3 seperate folders:




I processed step 1 and then attempted to upload to the cloud. Because there are duplicate file names I received an error. I followed the advice in this post:

and was able to open and save the project. When I later attempted to open the project I received the “Error e0400b”. From my forum searches it appears this is often related to using multiple version of Pix4D, but I’ve been using the same version. I also checked the .p4d file in Notepad++ and was unable to find the issue.

My .p4d file can be found here:

The log can be found here:

Any help would be most appreciated. I’d like to avoid having to re-pick the GCPs and process.

Hi Larry,

How are you opening the project? Are you opening it launching Pix4d software and then selecting the project from the suggested ones or browsing to it?

Could you try to launch the project directly double-clicking on the .p4d file?

Also, if this doesn’t work, could you re-upload the p4d file of the project as the link you provided takes me to a video?


Hi Alice,

I did try launching by double clicking, as well as the other way, with no success.

Oops, sorry about the link! Here’s the correct one:

I ended up just re-processing, so there’s no rush. I just wanted to make sure the team was aware of the issue.


Larry, sorry to hear you had to re-process. Thank you for reporting the issue. I’ll try to gather more information. Did reprocessing let you obtain the results you wanted?

It did, yes.

There were no further issues after re-processing. I suspect that it had something to do with the image locations. I’ve been moving files back and forth between two machines and it’s possible some image paths were altered.

I see. Yes, that could have corrupted the file somehow.