User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.159 Safari/537.36 Edg/92.0.902.78
Steps to reproduce:
After upgrading from the 78.x series to the 91.x series, I'm getting the dreaded Windows 10 pop-up every time I launch Thunderbird:
"There is no email program associated to perform the requested action. Please install an email program or, if one is already installed, create an association in the Default Programs control panel."
I've uninstalled and reinstalled the product, and I've naturally set Thunderbird as the default application for e-mail in the Windows 10 "Default Apps" control panel (and also using Thunderbird's own "Use Thunderbird as the default client" within the "System Integration" UI). Problem occurs on two Windows 10 PCs (same OS version, same TB version and same TB profile under %AppData%).
The registry also seems like it's in order:
"DLLPath"="C:\Program Files\Mozilla Thunderbird\mozMapi32_InUse.dll"
(followed by all the normal Thunderbird configuration you'd expect to appear at HKLM\SOFTARE\Clients\Mail\Mozilla Thunder)
The standard Windows 10 pop-up complaining that no e-mail program has been configured.
Thunderbird used to launch without complaint; getting this pop-up on every launch now asking me to set a default e-mail application.