The following TFS/VSTS error can occur if running a build or release from a 32-bit agent:
A supported task execution handler was not found. The task does not carry an implementation that is compatible with your current operating system 'Windows(X86)'. Contact the task author for more details.
This will occur because the tasks are not supported by the 32-bit agent.
When downloading an agent from TFS/VSTS, there is an option to download a 32-bit or 64-bit. You can resolve this by reinstalling the agent as 64-bit using the option outlined below.