Error e0400: "Cannot open project..." - PIX4Dmapper



When trying to open a project file (.p4d) using PIX4Dmapper, the project fails to load and one of the following messages is displayed:

e0400a. "Cannot open project... The project file does not exist."
e0400b. "Cannot open project... Invalid format."
e0400c. "Cannot open project... Project version is greater than the software version."
e0400d. "Cannot open project... Some of the image paths cannot be found."
e0400e. "Cannot open project... Cannot convert the project file to the latest format."
e0400f. "Cannot open project... The project needs to contain at least 3 enabled images."
e0400g. "Cannot open project... Non expected parsing error."



a. The project file does not exist.
The .p4d file has been moved or deleted and does not exist in this directory.

b. Invalid format.
A typical error is the XML validation that failed with XSD. The .p4d format conversion is automatic when upgrading a project, meaning when jumping from one version to a more recent one. However if the gap between versions is too big, the conversion might fail (e.g. from 3.0.1 to 4.0.1).

c. Project version is greater than software version.
By default, the .p4d file is not retro-compatible regarding the software version. As an example, it is not possible to open a project using 4.1.0 if the project was previously created or opened using 4.1.1.

d. Some of the image paths cannot be found.
The images of the project are moved to another location.

e. Cannot convert the project file to the latest format.
The .p4d file is too old and cannot be converted to the latest format.

f. The project needs to contain at least 3 enabled images.
Less than three images are enabled.

g. Non expected parsing error.




a. The project file does not exist.
Create a new project.

b. Invalid format.
Edit the .p4d file using a source code editor like Notepad++.


  1. Open the .p4d file using Notepad++.
  2. Go to line 35 and set the OptimizerType to Ceres.
  3. On the menu bar, click File > Save.

c. Project version is greater than software version.
Download and install the latest version via this link. Although downgrading the project version is not recommended, it is possible to edit the .p4d file using a source code editor like Notepad++.


  1. Open the .p4d file using Notepad++.
  2. Edit the projectVersion and p4dVersion. Check the .p4d file of another project having the older version format to know which values to put.
  3. On the menu bar, click File > Save.

d. Some of the image paths cannot be found.
Create a new project.

e. Cannot convert the project file to the latest format.
To convert a very old .p4d file, a smooth transition between versions is required. A project processed with a version should be opened with the next stable version). 

f. The project needs to contain at least 3 enabled images.
To be able to process the project, at least three images have the be used. To be able to process a project, create a new project.

g. Non expected parsing error.
Double click the P4D project file from Windows File Explorer rather than opening it from within PIX4Dmapper.


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Article feedback (for troubleshooting, post here instead)


  • Giang Bùi

    I can not open file demo. Hell please!

  • Holden (Pix4D)

    Hi Giang. Please open a support ticket by clicking "Contact Support" at the top of the page. Please provide a quality report and description of where the problem is occurring.

  • Leo Nguyen

    I'm not able to open a project that was processed on the web.  When it was complete and downloaded, I tried to open and first got a message that some of the image paths could not be found and to select a new directory.  I found that the images were actually missing from the downloaded folder, so I copied the images from the sd card into the folder, then selected that path.  But the box just keeps popping up again and again no matter how many times I select the folder.

    If I cancel the load and try again, the next error I get is Error e0400g, non expected parsing error.  If I shut down the program and restart it, it goes back to the other issue of not finding the path. 

    I'm unable to resolve this issue.

  • Daniel (Pix4D)

    Hi Leo,

    Would you tell us what is the cloud project you refer to?

    What is the desktop version that you are using?

    Thank you very much.


  • David Parker

    I'm trying to open a project in 4D Desktop that was processed in the cloud. I've successfully extracted all of the project files, navigated to the densification project data and the Mesh file (I want to create a fly-through), but the Mesh, Point Cloud and Densification Data all had the incorrect file extension:

    ".p4b" - note the 'b' instead of a 'd'.

    This meant I was initially unable to open them. I've now altered the file extension to the appropriate ".p4d", but I then receive the error:

    e0400b. "Cannot open project... Invalid format."

    The solution that is suggested here of opening the file in Notepad ++ and altering the code is ineffective as all of the code is in odd lettering (I have no idea where to even start with it - honestly, just identifying and changing the file extension is right on the edge of my programming comfort zone!).

    Could you please suggest an alternative solution?

  • Daniel (Pix4D)

    Hello David,

    The extension .p4d corresponds to the Pix4D project file.

    The extension .p4b is also a Pix4D extension and after a project is processed there are some files with that extension which correpond to the point cloud and mesh, there is nothing wrong in that. The same point cloud is also in LAS format and the 3DMesh can be exported in other formats too.

    The link that you added explains how to edit the project file (.p4d) only. The .p4b files do not have to be edited, please put them back to the extension that they had and try to open the p4d file with Pix4Dmapper.


  • David Parker

    Thank you for your response.

    I've now altered the extension back to .p4b, as suggested, but I'm now back to the original error:

    As an attempted work-around, I've now renamed the original .p4d project file to precisely match this one. It now opens in Pix4D, but there's no mesh or point cloud in Mapper. It seems that, despite the fact I'm using project files downloaded from the Cloud, I have to process the whole project again from scratch to generate a mesh (a process that I'd very much like to avoid!).

    All I want is to make a Pix4D fly-through of a 3D mesh that's been rendered in the cloud. It's proving infuriating.

  • tom hank


    pix4d merge two dtm value or not??  because i split my project in 3 parts

  • Daniel (Pix4D)

    Hello Tom,

    I am not sure if I understand your question.

    In order to merge two projects you should run Step1 in both projects and then merge them.

    More information can be found here: How to merge projects

    Once they have been merged, you can run Step2 and Step3 and if you select the DTM functionality, a DTM will be created covering the whole project. If you have two projects with 2 different DTMs, they cannot be merged within Pix4D.

    I hope this information helps.



  • Joachim Hovland

    Cannot open Highway demo project due to a e0400g error.
    Happens when I try to open it and the software tells me to update the files due to new patch in p4d.

    How can I fix this? All help to open it would be nice:)

  • Daniel (Pix4D)


    I would do the following.

    1. Log out of the Pix4D license
    2. Uninstall Pix4D
    3. Install the new 4.4.12 release
    4. Log in the software with your user and password
    5. Try to open the project again.

    Please let me know how it goes.


  • Helio Jose Medeiros

    Erro e0400a??????? Solucion??????

  • Rhéa (Pix4D)

    Hola Helio, el software tiene problemas en abrir el proyecto porque el camino tiene un carácter especial:

    Al crear proyectos, asegúrate de eso:

    • El nombre del proyecto NO utiliza caracteres especiales.
    • El camino donde se creará el proyecto NO utiliza caracteres especiales.
    • El nombre del proyecto y la ruta juntos contienen menos de 256 caracteres.

    Más en este artículo.

    Intenta abrir el proyecto directamente desde la interfaz del software.
    1. Abra Pix4Dmapper.
    2. Ve a Proyecto > Abrir proyecto...
    3. Navega hasta la ubicación del archivo P4D, Terreno.p4d.
    4. Selecciona el archivo Terreno.p4d y abra el proyecto.
    Hazme saber cómo te fue.

  • Susan Myers

    Hi.  I have updated to the latest versions of both Pix4Dcapture (4.11.0) on my iOS device, and Pix4Dmapper (4.6.1) on my PC. 

    I assumed these two would work together, but am receiving an error.  When opening the .p4d file using Pix4Dmapper on the PC, I am receiving the Error: e0400b: However, when I open the .p4d file in Notepad, I find no "Optimizer" in the file to replace.

    Need to plan my mission prior to flying.  Since we cannot send a map of our desired mission area to iOS Pix4Dcapture, but we can share the Pix4Dcapture planned mission area from the iOS back to the PC via email, am trying to open the shared mission Pix4D project created using Pix4Dcapture so that I can confirm it will cover the desired area.  

    Ultimately, I need the planned mission boundary point coordinates.  Thank you for your assistance.

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