Failed to build the project. Error code: 1

Japan Forum
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1

Good evening

I am a user of UiPath Studio 2026.0.201STS Community edition.

I am running the project from two PCs (PC1, PC2) with the project located in OneDrive.

I was able to run the project from PC1, but when I tried to run it from PC2, the project stopped working. I updated the package, deleted project.json, cache.nuget, and design.json, and after restarting the project, I saw the following error in the output panel.
Is there any recovery method?

[Information] Setting up environment
[Information] Execution completed
[Error] Project build failed. Error code: 1
2

Hi @gorby

Since the project is stored in OneDrive, first make sure PC2 has the same project files and package versions as PC1.

I would recommend making a copy of the project on PC2 (outside OneDrive), open it in Studio, restore the dependencies, and try Clean → Rebuild → Run.

If it still fails, please share the full build error from the Output panel. Project build failed. Error code: 1 alone doesn’t show the actual cause.

3

Hi @gorby ,
This error usually indicates that UiPath cannot build the project successfully on PC2, even though the workflow execution itself is not starting.

Try these recovery steps:

  1. Reinstall project dependencies

    • Open the project in Studio.
    • Go to Manage Packages → Repair Dependencies or reinstall missing packages.
    • Save and restart Studio.

  2. Clear local caches

    • Close Studio.
    • Delete:
      • %userprofile%\.nuget\packages
      • %localappdata%\UiPath\.cache
    • Reopen the project and restore dependencies.

  3. Check OneDrive synchronization

    • Make sure all project files are fully synced on PC2.
    • Verify that .xaml, project.json, and related files are not marked as online-only.

  4. Compare UiPath versions

    • Ensure both PC1 and PC2 are running the same Studio version and package versions.

  5. Look for build errors

    • Open the Error List panel in Studio.
    • Validate the project (Ctrl + Shift + F6) and check for missing activities, broken references, or compilation errors.

  6. Restore from PC1

    • If PC1 still opens the project correctly, copy the entire project folder from PC1 to PC2 instead of relying on the OneDrive copy.

Thanks

4

Hi, thank you for your advice.

PC1 is running Community Edition version 2026.0.197STS, while PC2 is running Community Edition version 2026.0.201STS.
Therefore, in order to do what you suggested, I would need to downgrade the Community Edition on PC2 from 2026.0.201STS to 2026.0.197STS.
Would such a downgrade be possible?

5

Hi, @Monali_Vekariya

Unfortunately, I cannot accept your proposal.
The reason is that I use OneDrive to share the same project between PC1 and PC2.
A method that copies the project locally from OneDrive cannot satisfy this requirement.

Cheers

6

The information shown in the Output panel consists of the three lines I indicated — that is all.

7

If it still fails, could you check the UiPath Studio logs on PC2 for the detailed build error? That should help identify the actual cause.

8

Hi @Monali_Vekariya ,

As per your request,I uploaded a UiPath.Studio.log
The following line in the uploaded file corresponds to the error in question.

19:07:59.4032 => [ERROR] [UiPath.Studio.App.Logging.OutputLogger] [1] プロジェクトの構築に失敗しました。エラー コード: 1

2026-09-08_UiPath.Studio.txt (253.1 KB)

Cheers

9

Could you please check the Studio.log file first? It should contain more details about the project build failure than execution.log.

10
  1. Close UiPath Studio.
  2. Make sure the project is fully synced in OneDrive.
  3. Right-click the project folder → Properties → Security and check that your user has read/write access.
  4. As a quick test, copy the project to a local folder such as C:\UiPathProjects\ and open it from there.

If the project works from the local folder, the issue is most likely related to OneDrive file access or locking.

12

Hi @Monali_Vekariya

I have confirmed that most of the files in the OneDrive project are synchronized with the local files, but since there are many project configuration files, it’s possible that I may have overlooked something.
If possible, could you tell me the exact file path of the file that you believe failed to synchronize?

Cheers

13

Hi @gorby,

The Studio version difference is actually the first thing I’d isolate now:

PC1 → 2026.0.197STS
PC2 → 2026.0.201STS

Since the same project works on PC1 and fails on PC2, I’d try to determine whether the failure follows the Studio version or the OneDrive/environment.

I wouldn’t delete project.json again, because that can remove useful information about the project’s intended dependencies.

I’d do these checks:

  1. Compare the package versions/resolved dependencies on both machines.

  2. Compare the exact contents of project.json from PC1 and PC2.

  3. Check whether PC2 has restored the same package versions as PC1.

  4. As a diagnostic test, open a copy of the project from a local folder on PC2. This doesn’t mean you need to abandon OneDrive; it just tells us whether OneDrive is involved.

  5. If the local copy still fails on 2026.0.201STS, the Studio version becomes a much stronger suspect.

  6. If possible, reproduce the project on a machine running 2026.0.197STS. If it immediately works, you’ve isolated the difference to the Studio/runtime environment.

Since the Studio log only seems to report the generic “Project build failed. Error code: 1”, I’d also compare the package restore/build logs rather than relying only on the Output panel.

One more important point: make sure PC1 and PC2 are not resolving different package versions even though the project.json looks the same. A package dependency can behave differently after restore if the available package versions/sources differ.

At this point I’d treat this as an environment/version comparison problem rather than a corrupted project.

If you can establish whether the project fails on a second machine running 2026.0.197STS, that would be a very useful next data point.

14

Hi,my passionate UiPath instructor @Roshan.Manchanayake

Thank you for the detailed response.
Since this project runs without any issues on PC1, I think I’ll just leave this issue as it is. :roll_eyes:
I know UiPath is always a bit puzzling. :face_with_spiral_eyes: