Yes, we're sure it was Extension Manager CC, because of the screenshots the customers sent.
You can download either one of the plugins that have been failing for some, from the sidebars on their product pages:
Let us know if we can help further in diagnosing this.
We've downloaded two extensions from web site you attached,but extensions were both installed successfully. All the files in the .mxi were copied to the right destination. At the same time, plugins of DocsFlow and WordsFlow both worked well. If the customers meet this issue again, please capture a .log file and send it to the email@example.com , so that we can do further research.
Thanks for checking!
Yes, they work for us, too, in-house, and for plenty of other customers, but we've had several recent reports of the installation supposedly being successful, but no files in the place the .mxi specified.
The problem is getting the .log file is tough--we have to ask the customer to go through that fairly complex dance, or try to do it ourselves. Any chance Extension Manager could always create and keep the most recent installation log, which we could ask the customer to send us after one of these apparently-worked-but-actually-failed installations?
Now we're also getting problems with "failed to verify signature", which seems to happen when the customer is behind a firewall or proxy. Is Extension Manager going out to the network in some non-standard fashion (non-HTTP, non-port 80)? Could you make that an optional verification step that doesn't force a failure but allows the customer to continue? Or just make it advisory rather than an error?
What's it verifying, anyway?
Actually, without ExManCoreLibLog.YES, EM CC will still create log file if there are warnings or errors but only WARNING, ERROR, CRITICAL and FATAL level messages are saved. If you create ExManCoreLibLog.YES, EM CC will save all level messages so more detailed context is available for troubleshooting.
As a temporary solution we will create an extension to copy ExManCoreLibLog.YES to the correct location when we have time so that users can install it to enable logging instead of using CLI which they are not familiar with. You can create it, too if you can't wait for it.
During signature validation, EM checks CRL (Certificate Revocation List) and timestamp online. To avoid online check failure, users can uncheck “Allow Extension Manager to access Internet” option in the Preferences dialog box then install the extension again.