bug: flet build fails with dependency with only `<`, The system cannot find the file specified.

[td3447]

Duplicate Check

• I have searched the opened issues and there are no duplicates

Describe the bug

Overview

When building an application using a dependency that requires using a < such as chardet<6 the build fails with an error of The system cannot find the file specified. after failing to build the app shell. The detail is not specific enough to let you know it is a dependency format issue.

Original setup for dependencies

dependencies = [
    "flet>=0.82.0",
     ...
    "chardet<6",
]

Code sample

Code

flet build apk -v

It works on any build command.

To reproduce

1. Define a dependency in pyproject.toml with package<3 with no space in front of the <
   • uv add chardet<6
2. run flet build from the root of your project
3. Flet will fail to build the app shell.

Expected behavior

Build completes.

Screenshots / Videos

Captures

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Operating System

Windows

Operating system details

Windows 11

Flet version

0.82+

Regression

I'm not sure / I don't know

Suggestions

When using uv to add dependencies, you must add it like uv add chardet<6 as uv add chardet <6 will fail. It would be nice to have it match that format. Or have a more detailed error message to catch this issue.

Current Fix

Do one of the following

Requirement Format	Description
chardet==5.2.0	Exact version
chardet >=5.0.0, <6	Any version range
chardet <6	Must include a space in front of the <

Logs

Logs

[23:32:53] Run subprocess: ['C:\\dev\\flutter\\bin\\flutter.BAT', '--version', '--no-version-check', '--suppress-analytics']                                                                                                                                                
[23:32:54]  Flutter executable: C:\dev\flutter\bin\flutter.BAT
            Dart executable: C:\dev\flutter\bin\dart.BAT
            Configuring Flutter's path to JDK
            Run subprocess: ['C:\\dev\\flutter\\bin\\flutter.BAT', 'config', '--no-version-check', '--suppress-analytics', '--jdk-dir=C:\\Program Files\\Eclipse Adoptium\\jdk-17.0.18.8-hotspot\\']                                                                         
            Setting "jdk-dir" value to "C:\Program Files\Eclipse Adoptium\jdk-17.0.18.8-hotspot\".
            You may need to restart any open editors for them to read new settings.

[23:32:55]  JDK installed ✅
            Android SDK installation found at C:\Users\user\AppData\Local\Android\Sdk
            Android SDK package "cmdline-tools;latest" is already installed
            Android SDK package "platform-tools" is already installed
            Android SDK package "platforms;android-35" is already installed
            Android SDK package "build-tools;34.0.0" is already installed
            Android SDK installed ✅

[23:32:59]  Created app shell ✅
            Run subprocess: ['C:\\dev\\flutter\\bin\\dart.BAT', 'run', '--suppress-analytics', 'serious_python:main', 'package', 'C:\\myapp\\src', '--platform', 'Android', '-r', 'chardet<6', '-r', 'flet-charts>=0.82.0', '-r',
            'flet-datatable2>=0.82.0', '-r', 'flet-secure-storage>=0.82.0', '-r', 'flet>=0.82.0', '-r', 'python-dotenv>=1.2.2', '--exclude', 'build', '--cleanup-packages']                                                                                                  
            The system cannot find the file specified.  <- [❗ERROR MESSAGE❗]


            Run subprocess: ['C:\\dev\\flutter\\bin\\flutter.BAT', 'doctor', '--no-version-check', '--suppress-analytics']                                                                                                                                                   
[23:33:03] Doctor summary (to see all details, run flutter doctor -v):
           [√] Flutter (Channel stable, 3.41.4, on Microsoft Windows [Version 10.0.26200.8037], locale en-US)                                                                                                  
           [√] Windows Version (Windows 11 or higher, 25H2, 2009)                                  
           [√] Android toolchain - develop for Android devices (Android SDK version 36.0.0)     
           [√] Chrome - develop for the web                                                 
           [√] Visual Studio - develop Windows apps (Visual Studio Community 2022 17.14.28)
           [√] Connected device (3 available)                                    
           [√] Network resources                                                           
           • No issues found!                                                                                                                                            
╭──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮                                           
│ Error building Flet app - see the log of failed command above.                                                                                                                                                                                                           │                                           
╰──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯ 

Additional details

Original Discord Discussion

[Creeper19472]

Same issue found here: #6253 (comment)

[td3447]

Same issue found here: #6253 (comment)

This is similar, but I think the issue is that flet build is still not accounting for the lack of a space between the module and the <.

This was the proposed fix

chardet<6 is how uv adds the dependency and how it was recommended to fix, but chardet <6 is how the build will work correctly.

it also does not work with 0.82