addons.xpi	DEBUG	Cancelling download of https://addons.cdn.mozilla.net/user-media/addons/387429/reddit_enhancement_suite-4.6.1-fx.xpi
addons.xpi	DEBUG	removeTemporaryFile: https://addons.cdn.mozilla.net/user-media/addons/387429/reddit_enhancement_suite-4.6.1-fx.xpi does not own temp file
[Exception... "Component returned failure code: 0x80004001 (NS_ERROR_NOT_IMPLEMENTED) [nsIURI.hostPort]"  nsresult: "0x80004001 (NS_ERROR_NOT_IMPLEMENTED)"  location: "JS frame :: resource://gre/modules/PopupNotifications.jsm :: PopupNotifications_refreshPanel/< :: line 667"  data: no]
PopupNotifications_refreshPanel/<()
 PopupNotifications.jsm:671
forEach()
 self-hosted:232
PopupNotifications_refreshPanel()
 PopupNotifications.jsm:616
PopupNotifications_showPanel()
 PopupNotifications.jsm:728
PopupNotifications_update()
 PopupNotifications.jsm:844
PopupNotifications_show()
 PopupNotifications.jsm:394
gXPInstallObserver.observe()
 browser-addons.js:267
extWebInstallListener.prototype.onWebInstallOriginBlocked()
 amWebInstallListener.js:306
AddonManagerInternal.installAddonsFromWebpage()
 AddonManager.jsm:2158
this.AddonManager.installAddonsFromWebpage()
 AddonManager.jsm:3214
buildNextInstall()
 addonManager.js:92
amManager.prototype.installAddonsFromWebpage/buildNextInstall/<()
 addonManager.js:134
safeCall()
 AddonManager.jsm:179
getInstallForURL_safeCall()
 AddonManager.jsm:1890
this.XPIProvider.getInstallForURL/<()
 XPIProvider.jsm:3784
makeSafe/<()
 XPIProvider.jsm:1922
AddonInstall.prototype.initAvailableDownload()
 XPIProvider.jsm:5263
AddonInstall.createDownload()
 XPIProvider.jsm:6251
this.XPIProvider.getInstallForURL()
 XPIProvider.jsm:3783
callProviderAsync()
 AddonManager.jsm:254
AddonManagerInternal.getInstallForURL()
 AddonManager.jsm:1887
this.AddonManager.getInstallForURL()
 AddonManager.jsm:3135
buildNextInstall()
 addonManager.js:96
amManager.prototype.installAddonsFromWebpage()
 addonManager.js:137
amManager.prototype.receiveMessage()
 addonManager.js:173
 PopupNotifications.jsm:671:0

Hey SUMO people, As an add-on reviewer, I have to install add-ons frequently. However, these past few weeks I can no longer install add-ons by opening a direct url to an .xpi file nor click any link to an .xpi on amo (such as on a review page). It always results in the "Firefox Developer Edition/Nightly/Firefox prevented this site from asking you to install software on your computer." Looking at the Browser Console, I can see the following error messages (see below this paragraph). It seems to have something to do with filesystem permissions; and Firefox doesn't catch this error message and likely just borks and shows the default blocked unsigned add-on doorhanger/pop-up notification. I've tried recursively icacls-resetting both my profile directory and my %temp% folder to no avail. Does anyone know how to fix this? If you need me to perform any steps to triage/debug this issue, let me know. <pre>addons.xpi DEBUG Cancelling download of https://addons.cdn.mozilla.net/user-media/addons/387429/reddit_enhancement_suite-4.6.1-fx.xpi addons.xpi DEBUG removeTemporaryFile: https://addons.cdn.mozilla.net/user-media/addons/387429/reddit_enhancement_suite-4.6.1-fx.xpi does not own temp file [Exception... "Component returned failure code: 0x80004001 (NS_ERROR_NOT_IMPLEMENTED) [nsIURI.hostPort]" nsresult: "0x80004001 (NS_ERROR_NOT_IMPLEMENTED)" location: "JS frame :: resource://gre/modules/PopupNotifications.jsm :: PopupNotifications_refreshPanel/< :: line 667" data: no] PopupNotifications_refreshPanel/<() PopupNotifications.jsm:671 forEach() self-hosted:232 PopupNotifications_refreshPanel() PopupNotifications.jsm:616 PopupNotifications_showPanel() PopupNotifications.jsm:728 PopupNotifications_update() PopupNotifications.jsm:844 PopupNotifications_show() PopupNotifications.jsm:394 gXPInstallObserver.observe() browser-addons.js:267 extWebInstallListener.prototype.onWebInstallOriginBlocked() amWebInstallListener.js:306 AddonManagerInternal.installAddonsFromWebpage() AddonManager.jsm:2158 this.AddonManager.installAddonsFromWebpage() AddonManager.jsm:3214 buildNextInstall() addonManager.js:92 amManager.prototype.installAddonsFromWebpage/buildNextInstall/<() addonManager.js:134 safeCall() AddonManager.jsm:179 getInstallForURL_safeCall() AddonManager.jsm:1890 this.XPIProvider.getInstallForURL/<() XPIProvider.jsm:3784 makeSafe/<() XPIProvider.jsm:1922 AddonInstall.prototype.initAvailableDownload() XPIProvider.jsm:5263 AddonInstall.createDownload() XPIProvider.jsm:6251 this.XPIProvider.getInstallForURL() XPIProvider.jsm:3783 callProviderAsync() AddonManager.jsm:254 AddonManagerInternal.getInstallForURL() AddonManager.jsm:1887 this.AddonManager.getInstallForURL() AddonManager.jsm:3135 buildNextInstall() addonManager.js:96 amManager.prototype.installAddonsFromWebpage() addonManager.js:137 amManager.prototype.receiveMessage() addonManager.js:173 PopupNotifications.jsm:671:0</pre>