MobileRead Forums - View Single Post - Installed Calibre won't open, downloaded won't install

RBW · 04-07-2023, 09:24 PM

Absolute beginner on Forum, but long time user of Calibre.

1. Installed version which worked last week in Windows 11 environment gives error message "This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem."

2. Downloaded new version 6.15 (tried three times, same result), when double clicked to install gives error message "This installation package could not be opened. Contact the application vendor to verify that this is a valid Windows Installer package"

3. Read old threads on this issue with older versions of Windows. Checked permissions and believe I have Full Control (properties, security).

4. Have Webroot security - don't see issue there (but may not be looking in right place).

Please help.

04-07-2023, 09:24 PM	#1
RBW Junior Member Posts: 3 Karma: 10 Join Date: Apr 2023 Device: Samsung laptop but changes often	Installed Calibre won't open, downloaded won't install Absolute beginner on Forum, but long time user of Calibre. 1. Installed version which worked last week in Windows 11 environment gives error message "This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem." 2. Downloaded new version 6.15 (tried three times, same result), when double clicked to install gives error message "This installation package could not be opened. Contact the application vendor to verify that this is a valid Windows Installer package" 3. Read old threads on this issue with older versions of Windows. Checked permissions and believe I have Full Control (properties, security). 4. Have Webroot security - don't see issue there (but may not be looking in right place). Please help.