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Version: 5.0

Configure Version

FluentHttpClient provides simple, readable extensions for configuring both the request version and its negotiation behavior.

Setting HTTP Version​

These overloads assign a specific HTTP version to the request. They do not enforce negotiation behavior unless a version policy is also specified.

Using a Version String​

builder.UsingVersion("2.0");
  • Throws if the string is null/empty/whitespace.
  • Validates the version with Version.TryParse.
  • Common examples: "1.1", "2.0", "3.0".

Using Major/Minor Components​

builder.UsingVersion(1, 1);

Creates a Version instance using the numeric components.

Using Version Instance​

builder.UsingVersion(new Version(2, 0));
  • Throws if version is null.
  • Useful when version objects are constructed elsewhere.

Setting Version and Policy​

important

Setting the version policy is only supported in NET 5.0+.

The HttpVersionPolicy enum controls how HttpRequestMessage.Version is interpreted:

  • RequestVersionExact
  • RequestVersionOrLower
  • RequestVersionOrHigher

Combined with explicit version selection, these extensions let you control fallback behavior and protocol negotiation.

Version String and Policy​

builder.UsingVersion("2.0", HttpVersionPolicy.RequestVersionExact);

Version Instance Policy​

builder.UsingVersion(new Version(3, 0), HttpVersionPolicy.RequestVersionOrLower);

Both overloads:

  • Set builder.Version.
  • Set builder.VersionPolicy.
  • Throw if version is null (for the Version overload).

Setting Version Policy​

important

Setting the version policy is only supported in NET 5.0+.

builder.UsingVersionPolicy(HttpVersionPolicy.RequestVersionOrHigher);
  • Leaves the previously assigned version intact.
  • Applies only the policy.

Behavior Notes​

Most applications never need to manually set the HTTP version - HttpClient negotiates the best protocol the server and handler support. However, there are still practical scenarios where explicitly specifying the version or version policy is useful.

You might override the HTTP version to:

  • Force HTTP/1.1 for servers, proxies, or middleware that do not behave correctly with HTTP/2.
  • Opt into HTTP/2 where multiplexing, header compression, or improved performance is available and required.
  • Test behavior across protocol versions during diagnostics or compatibility checks.
  • Control fallback behavior using HttpVersionPolicy (e.g., require an exact match or permit downgrade).

Quick Reference​

MethodPurpose
UsingVersion(string)Set version using a string such as "1.1" or "2.0".
UsingVersion(int, int)Set version using major/minor components.
UsingVersion(Version)Set version from a Version instance.
UsingVersion(string, HttpVersionPolicy)Set version and policy (NET 5.0+).
UsingVersion(Version, HttpVersionPolicy)Set version and policy (NET 5.0+).
UsingVersionPolicy(HttpVersionPolicy)Set negotiation policy only (NET 5.0+).