Contents

1. FAQ -- common run-time errors
   1. Plugin loader failure 1
   2. Plugin loader failure 2
   3. (Windows) Qt 5 cannot find platform plugin "windows"

FAQ -- common run-time errors

Plugin loader failure 1

Error message

000038 [2014-02-28 15:50:58.750509] <error> cannot load plugin 'PluginName.dll'. Plugin loader returned error: The shared library was not found.

Solution

See ​http://qt-project.org/doc/qt-5/deployment-plugins.html for more information about development of Qt plugins. You can set QT_DEBUG_PLUGINS environment variable to a non-zero value to see more information from plugin loader.

1. Check if filename 'PluginName.dll' is correct in your XML file.
2. Check if the correct version (release/debug) is used, see plugins postfix attribute in the XML.
3. Check if this file exists in the same directory as the executable.

Plugin loader failure 2

Error message

000038 [2014-02-28 15:50:58.750509] <error> cannot load plugin 'PluginName.dll'. Plugin loader returned error: Cannot load library .//PluginName.dll: ...message in your language...

Solution

See ​http://qt-project.org/doc/qt-5/deployment-plugins.html for more information about development of Qt plugins. You can set QT_DEBUG_PLUGINS environment variable to a non-zero value to see more information from plugin loader.

1. Check if this component CMakeLists.txt uses create_export and pacpus_plugin macros and that it adds generated files to the source file list, e.g.:

   create_export(EXPORT_HDR ${PROJECT_NAME})
   pacpus_plugin(PLUGIN_CPP PLUGIN_H ${PROJECT_NAME})
   
   set(SRCS
       ${PLUGIN_CPP}
       ...
   )
   

2. Check for the missing DLL's dependencies, other DLLs can be missing (verify it using e.g. DependencyWalker). (Windows) Copy DLLs to the application's folder or add their folder to PATH. (Unix) Make them visible to the linker.
3. (Windows) Check if the .dll file exports any symbols (using e.g. DependencyWalker). At least qt_plugin_instance and qt_plugin_query_metadata should be visible exported symbols.
4. Check if the application, the plugin and its dependencies have been built in the same release/debug version.
5. Check if the application, the plugin and its dependencies have been built using the same compiler version. (Windows) Look for dependent DLLs like MSVCP110.dll or MSVCR110.dll, check that the version, here 11.0, corresponds with your compiler and the version used by other DLLs.

(Windows) Qt 5 cannot find platform plugin "windows"

Error message

Solution

Copy folder "%QT_DIR%\plugins\platforms" to the folder where your application is executed (so that it has a subfolder "platforms".