If you are getting an error on Mobile Browsers when trying to open PDF stored in SharePoint, that’s no more surprise as its been purposely disabled by Latest Office Web Apps 2013 Capabilities. This capability has been removed as of Office Web Apps October 2013 Cumulative Update.
That doesn’t mean you can’t open PDF files in mobile browsers at all. The default OWA action is to open PDF files in WordPDF Application. To overcome this behavior, we can remove the WordPDF binding from OWA and let it open by Ifilter as default. Run the following command in SharePoint Application server where you configured OWA WOPI Binding. This command will remove the WordPDF Application Binding from your SharePoint farm. This won’t harm any other applications such as Word, Excel or PPTX.
Get-SPWOPIBinding -Action “view” -Application “WordPDF”| Remove-SPWOPIBinding Removing the Binding for the WordPDF application will allow all the mobile devices to open PDF files from the browser normally without utilizing OWA WORD Application.
Microsoft Cloud Infrastructure Technical Journal 
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