Hi,
i have the same problem. I use Cura 4.8.0. I haven't found a solution in the forum.
I deactivated the firewall but that doesn't work either.
attached the last log files:
2021-04-12 13:32:38,026 - INFO - [MainThread] cura.Machines.MachineErrorChecker._setResult [214]: Error check finished, result = False, time = 7.2s
2021-04-12 13:32:41,775 - DEBUG - [MainThread] Toolbox.src.Toolbox._createDialog [216]: Marketplace: Creating dialog [Toolbox.qml].
2021-04-12 13:32:42,416 - DEBUG - [MainThread] Toolbox.src.Toolbox._makeRequestByType [544]: Requesting [packages] metadata from server.
2021-04-12 13:32:42,416 - DEBUG - [MainThread] Toolbox.src.Toolbox._makeRequestByType [544]: Requesting [authors] metadata from server.
2021-04-12 13:32:42,416 - DEBUG - [MainThread] Toolbox.src.Toolbox._updateInstalledModels [270]: Found a plugin that was installed with the old plugin browser: VersionUpgrade47to48
2021-04-12 13:32:44,183 - DEBUG - [MainThread] UM.TaskManagement.HttpRequestManager._onRequestError [374]: request[8e80353f][get][PyQt5.QtCore.QUrl('https://api.ultimaker.com/cura-packages/v1/cura/v7.4.0/packages')][timeout=None][no-data] got an error 6, SSL handshake failed
2021-04-12 13:32:44,186 - ERROR - [MainThread] Toolbox.src.Toolbox._onDataRequestError [587]: Request [packages] failed due to error [6]: SSL handshake failed
2021-04-12 13:32:44,198 - DEBUG - [MainThread] UM.TaskManagement.HttpRequestManager._onRequestError [374]: request[c4e6a516][get][PyQt5.QtCore.QUrl('https://api.ultimaker.com/cura-packages/v1/cura/v7.4.0/authors')][timeout=None][no-data] got an error 6, SSL handshake failed
2021-04-12 13:32:44,202 - ERROR - [MainThread] Toolbox.src.Toolbox._onDataRequestError [587]: Request [authors] failed due to error [6]: SSL handshake failed
2021-04-12 13:32:47,184 - DEBUG - [MainThread] cura.AutoSave._onTimeout [59]: Autosaving preferences, instances and profiles
2021-04-12 13:33:01,176 - DEBUG - [MainThread] UM.TaskManagement.HttpRequestManager._onRequestError [374]: request[11aab6b9][get][PyQt5.QtCore.QUrl('https://api.ultimaker.com/connect/v1/clusters?status=active')][timeout=10][no-data] got an error 6, SSL handshake failed
2021-04-12 13:33:01,183 - DEBUG - [MainThread] UM.TaskManagement.HttpRequestManager._onRequestError [374]: request[8e52bd46][get][PyQt5.QtCore.QUrl('https://api.ultimaker.com/cura-packages/v1/user/packages')][timeout=10][no-data] got an error 6, SSL handshake failed
2021-04-12 13:33:01,184 - WARNING - [MainThread] Toolbox.src.CloudSync.CloudPackageChecker._onUserPackagesRequestFinished [76]: Requesting user packages failed, response code None while trying to connect to PyQt5.QtCore.QUrl('https://api.ultimaker.com/cura-packages/v1/user/packages')
