Cannot open the project file when the export folder is defined by UNC path

[jpdupuy]

Describe the issue

On Windows 10, QField reports an error when opening a local project file which has been defined in an export folder based on a UNC path (network folder)

Reproduction steps

Steps to reproduce the behavior:

1. Configure QFieldSync to Export your project (cable export) in a network folder instead on C:/users//QField/export/ (see screenshot)
2. Install QField for Windows on your desktop
3. Open QField on your desktop, and select "a local project"
4. Select your exported project from from network folder

Expected behavior

The map should be displayed without error message

Observed behavior

A blank map and an error message (see screenshot): Le fichier de projet "/QFieldProjet/Infrastructure/Export/GAZ_qfcloud_edu_qfield.qgs" n'existe pas

Screenshots and GIFs

[Please also attach additional files if a specific project/dataset is useful to investigate the problem.]

Desktop (please complete the following information)

• OS: [Windows]
• QGIS Version [3.28.4]
• QFieldSync Version [4.4.8]

Mobile (please complete the following information)

• Device: [Desktop]
• OS: [Windows 10]
• QField version: [2.7.0)]

Additional information

• Problem started happening recently, didn't happen in an older version of QField: [No]
• Problem can be reliably reproduced, doesn't happen randomly: [Yes]
• Problem happens with all files and projects, not only some files or projects: [Yes]

[If the problem happened with QFieldCloud, please add your username and project name.]