The request for path /DynamicsNAV130/dev/metadata failed with code InternalServerError. Reason: NetFx40_LegacySecurityPolicy is enabled and must be turned off in the Microsoft.Dynamics.Nav.Server.exe.config file.

Open the file

C:\Program Files\Microsoft Dynamics 365 Business Central\130\Service\Microsoft.Dynamics.Nav.Server.exe.CONFIG

and set NetFx40_LegacySecurityPolicy = False

<add key=”NetFx40_LegacySecurityPolicy” value=”false”/>