Problem installing packages

Dear colleagues,

I am trying to install different solvers for JuMP but I am getting this errors:

Pkg.add("Ipopt")
INFO: Cloning cache of Ipopt from https://github.com/JuliaOpt/Ipopt.jl.git
INFO: Installing Ipopt v0.3.0
INFO: Building Ipopt
WARNING: imported binding for srcdir overwritten in module __anon__
Info: Downloading https://github.com/staticfloat/IpoptBuilder/releases/download/v3.12.8-9/Ipopt.x86_
64-w64-mingw32.tar.gz to C:\JuliaPro-0.6.2.2\pkgs-0.6.2.2\v0.6\Ipopt\deps\usr\downloads\Ipopt.x86_64
-w64-mingw32.tar.gz...
Exception setting "SecurityProtocol": "Cannot convert null to type "System.Net.SecurityProtocolType
" due to invalid enumeration values. Specify one of the following enumeration values and try again.
 The possible enumeration values are "Ssl3, Tls"."
At line:1 char:35
+ [System.Net.ServicePointManager]:: <<<< SecurityProtocol =
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : PropertyAssignmentException

Exception calling "DownloadFile" with "2" argument(s): "The underlying connection was closed: An un
expected error occurred on a send."
At line:4 char:24
+ $webclient.DownloadFile <<<< ("https://github.com/staticfloat/IpoptBuilder/releases/download/v3.1
2.8-9/Ipopt.x86_64-w64-mingw32.tar.gz", "C:\JuliaPro-0.6.2.2\pkgs-0.6.2.2\v0.6\Ipopt\deps\usr\downl
oads\Ipopt.x86_64-w64-mingw32.tar.gz")
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : DotNetMethodException

==========================================[ ERROR: Ipopt ]==========================================


LoadError: Could not download https://github.com/staticfloat/IpoptBuilder/releases/download/v3.12.8-
9/Ipopt.x86_64-w64-mingw32.tar.gz to C:\JuliaPro-0.6.2.2\pkgs-0.6.2.2\v0.6\Ipopt\deps\usr\downloads\
Ipopt.x86_64-w64-mingw32.tar.gz
while loading C:\JuliaPro-0.6.2.2\pkgs-0.6.2.2\v0.6\Ipopt\deps\build.jl, in expression starting on l
ine 13

====================================================================================================


==========================================[ BUILD ERRORS ]==========================================


WARNING: Ipopt had build errors.

 - packages with build errors remain installed in C:\JuliaPro-0.6.2.2\pkgs-0.6.2.2\v0.6
 - build the package(s) and all dependencies with `Pkg.build("Ipopt")`
 - build a single package by running its `deps/build.jl` script

====================================================================================================

Also, I have try to use the Pkg.build I get:


julia> Pkg.build("Ipopt")
INFO: Building Ipopt
WARNING: imported binding for srcdir overwritten in module __anon__
Info: Downloading https://github.com/staticfloat/IpoptBuilder/releases/download/v3.12.8-9/Ipopt.x86_
64-w64-mingw32.tar.gz to C:\JuliaPro-0.6.2.2\pkgs-0.6.2.2\v0.6\Ipopt\deps\usr\downloads\Ipopt.x86_64
-w64-mingw32.tar.gz...
Exception setting "SecurityProtocol": "Cannot convert null to type "System.Net.SecurityProtocolType
" due to invalid enumeration values. Specify one of the following enumeration values and try again.
 The possible enumeration values are "Ssl3, Tls"."
At line:1 char:35
+ [System.Net.ServicePointManager]:: <<<< SecurityProtocol =
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : PropertyAssignmentException

Exception calling "DownloadFile" with "2" argument(s): "The underlying connection was closed: An un
expected error occurred on a send."
At line:4 char:24
+ $webclient.DownloadFile <<<< ("https://github.com/staticfloat/IpoptBuilder/releases/download/v3.1
2.8-9/Ipopt.x86_64-w64-mingw32.tar.gz", "C:\JuliaPro-0.6.2.2\pkgs-0.6.2.2\v0.6\Ipopt\deps\usr\downl
oads\Ipopt.x86_64-w64-mingw32.tar.gz")
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : DotNetMethodException

==========================================[ ERROR: Ipopt ]==========================================


LoadError: Could not download https://github.com/staticfloat/IpoptBuilder/releases/download/v3.12.8-
9/Ipopt.x86_64-w64-mingw32.tar.gz to C:\JuliaPro-0.6.2.2\pkgs-0.6.2.2\v0.6\Ipopt\deps\usr\downloads\
Ipopt.x86_64-w64-mingw32.tar.gz
while loading C:\JuliaPro-0.6.2.2\pkgs-0.6.2.2\v0.6\Ipopt\deps\build.jl, in expression starting on l
ine 13

====================================================================================================


==========================================[ BUILD ERRORS ]==========================================


WARNING: Ipopt had build errors.

 - packages with build errors remain installed in C:\JuliaPro-0.6.2.2\pkgs-0.6.2.2\v0.6
 - build the package(s) and all dependencies with `Pkg.build("Ipopt")`
 - build a single package by running its `deps/build.jl` script

====================================================================================================

I hope that you can help me.

This looks like the same issue as Problems with CodecZlib

Do the suggestions from that thread help in your case?