A Reader-enabled plug-in that successfully loaded with Reader 4.05 does not load in Reader 5 due to the "Certified Plug-ins Only" preference being selected.
Issue
A Reader-enabled plug-in that successfully loads with Reader 4.05 does not load in Reader 5. There are no error messages, the plug-in is simply not recognized by Reader 5. The plug-in is digitally signed to work with the Reader (Reader-enabled).
Solution
Uncheck the "Certified Plug-ins Only" checkbox located on the Edit > Preferences > Options tab. Unchecking this setting and restarting Reader will allow Reader-enabled Plug-ins to load successfully.
Please note that unchecking "Certified Plug-ins Only" prevents some documents that use the WebBuy security handler from loading. Whether a document is affected or not depends on the publisher. PDF Merchant, one such publisher of documents that use the WebBuy security handler, has an option to prevent the document from being opened if non-certified plug-ins are allowed.
The web installer for Acrobat Reader 5.0 for Windows, located on the Adobe.com website at
http://www.adobe.com/products/acrobat/readstep2.html, installs Acrobat Reader 5.0 with the "Certified Only Plug-ins" preference checked (enabled).
The Reader installer located on the Acrobat 5 for Windows product CD installs Reader with this preference unchecked (disabled), as do installers for Reader 5 for the Mac OS.
The Reader-enabling process that "signs" a plug-in via digital certificate to allow it to load with Reader does not "certify" it to load with the "Certified Plug-ins Only" setting checked.
Notes for plug-in developers
You can instruct your clients to uncheck this preference, or you can alter the registry settings to change the Acrobat Reader 5.0 settings to launch Reader without the preference to load only Certified plug-ins enabled. Be sure that your Reader-enabled plug-in is in the Reader plug-ins directory. If there are no third party plug-ins present, Reader will not run outside trusted mode. If you have one of your plug-ins in the \plug_ins directory when Reader re-starts, the box will remain un-checked.
The Windows registry keys that this preference is stored under are:
HKEY_CURRENT_USER\Software\Adobe\AcrobatReader\5.0\AdobeViewer\TrustedMode
HKEY_USERS\.DEFAULT\Software\Adobe\AcrobatReader\5.0\AdobeViewer\TrustedMode
Under the Mac OS, these settings are stored in the Preferences folder located in the System Folder in a file named "Acrobat Reader 5 Prefs.plist." If you delete this file and restart the Reader, a new "Acrobat Reader 5 Prefs.plist" file will be created with the Certified Plug-ins Only option disabled. Within this file, when the "Certified Plug-ins Only" option is checked, a key, "avpTrustedMode", is created; when unchecked, the key is deleted. Programmatically deleting this key would also uncheck the option.
Adobe would welcome you making these changes to your plug-in if your plug-in complies with the IKLA you entered into with Adobe. Please note that Adobe may be terminating earlier versions of the IKLA in favor of the current agreement, located on the Adobe web site at
http://partners.adobe.com/asn/developer/acrosdk/pdfs/readerlic.pdf. For planning purposes, you may want to ensure that your plug-in complies with the terms and conditions on this version of the agreement.