Comment 4 for bug 709961

The file '~/.config/inkscape/extension-error.log' contains all information about extensions that failed to load, and the reasons why. AFAIK there used to be a notification about the extensions log when launching Inkscape - however, it was later disabled because it caused to much confusion (bug #166288 and several duplicates, bug #170609).

One problem is that this information can change any time between two inkscape sessions, yet visually notifying users each time Inkscape launches (e.g. every time the user double-clicks a file in the file-manager and thus launches a new Inkscape process) is hardly user-friendly and likely to interrupt many workflows.

The information from the extensions error log should be parsed and e.g. listed in a separate pane of the preferences dialog, or the 'About Inkscape' dialog:
Bug #170622 in Inkscape: “About|Extensions Dialog”

In the meantime - maybe someone contributes an extension which parses the log file and reports this information on demand as feedback from the extension script?