browser.download.dir
browser.download.downloadDir
browser.download.folderList
browser.download.lastDir
browser.download.useDownloadDir

Hello, Here are some ways to troubleshoot it : '''Check the Downloads panel for blocked downloads''' Firefox includes a download protection feature to protect you from malicious or potentially harmful file downloads. '''Clear the download history''' #Click the Downloads button, and then click Show all downloads. The Downloads window will open. #In the Downloads window, click Clear Downloads. #Close the Downloads window. '''Choose a different download folder''' #Click the menu button and select Settings. #Select the General panel. #Find the Downloads section under Files and Applications. #Click the Browsebutton next to the Save files to entry. #Choose a different download folder for saving files. #Close the Settings page. Any changes you've made will automatically be saved. '''Reset the download folder''' (advanced) #Type about:config in the address bar and press Enter. #A warning page may appear. Click Accept the Risk and Continue to go to the about:config page. #In the Search field, enter browser.download. #If any of the following settings are in bold text, reset their values. To reset a value, click the Delete Fx71aboutconfig-DeleteButton or Reset Fx71aboutconfig-ResetButton button, depending on the preference: browser.download.dir browser.download.downloadDir browser.download.folderList browser.download.lastDir browser.download.useDownloadDir If desired, you can revert back to your preferred download folder settings in your Firefox Settings General panel, in the Downloads section under Files and Applications. For more in Depth detail and additional solutions if the solutions above don't work, refer to this article : https://support.mozilla.org/en-US/kb/cant-download-or-save-files#firefox:win10:fx149