@@ -99,11 +99,9 @@ const DummyHost = "api.moby.localhost"

 // This version may be lower than the version of the api library module used.

 const MaxAPIVersion = "1.52"

-// fallbackAPIVersion is the version to fallback to if API-version negotiation

-// fails. This version is the highest version of the API before API-version

-// negotiation was introduced. If negotiation fails (or no API version was

-// included in the API response), we assume the API server uses the most

-// recent version before negotiation was introduced.

+// fallbackAPIVersion is the version to fall back to if API-version negotiation

+// fails. API versions below this version are not supported by the client,

+// and not considered when negotiating.

 const fallbackAPIVersion = "1.24"

 // Ensure that Client always implements APIClient.

@@ -311,8 +309,7 @@ func (cli *Client) ClientVersion() string {

 // If the API server's ping response does not contain an API version, or if the

 // client did not get a successful ping response, it assumes it is connected with

 // an old daemon that does not support API version negotiation, in which case it

-// downgrades to the latest version of the API before version negotiation was

-// added (1.24).

+// downgrades to the lowest supported API version.

 func (cli *Client) NegotiateAPIVersion(ctx context.Context) {

 	if !cli.manualOverride {

 		// Avoid concurrent modification of version-related fields

@@ -337,10 +334,8 @@ func (cli *Client) NegotiateAPIVersion(ctx context.Context) {

 // ([EnvOverrideAPIVersion]) environment variable, or if the client is initialized

 // with a fixed version ([WithVersion]), no negotiation is performed.

 //

-// If the API server's ping response does not contain an API version, we assume

-// we are connected with an old daemon without API version negotiation support,

-// and downgrade to the latest version of the API before version negotiation was

-// added (1.24).

+// If the API server's ping response does not contain an API version, it falls

+// back to the oldest API version supported.

 func (cli *Client) NegotiateAPIVersionPing(pingResponse types.Ping) {

 	if !cli.manualOverride {

 		// Avoid concurrent modification of version-related fields

@@ -355,8 +350,6 @@ func (cli *Client) NegotiateAPIVersionPing(pingResponse types.Ping) {

 // API version from the ping response.

 func (cli *Client) negotiateAPIVersionPing(pingVersion string) {

 	pingVersion = strings.TrimPrefix(pingVersion, "v")

-

-	// default to the latest version before versioning headers existed

 	if pingVersion == "" {

 		pingVersion = fallbackAPIVersion

 	}

@@ -303,9 +303,8 @@ func checkResponseErr(serverResp *http.Response) (retErr error) {

 			daemonErr = errors.New(strings.TrimSpace(errorResponse.Message))

 		}

 	} else {

-		// Fall back to returning the response as-is for API versions < 1.24

-		// that didn't support JSON error responses, and for situations

-		// where a plain text error is returned. This branch may also catch

+		// Fall back to returning the response as-is for situations where a

+		// plain text error is returned. This branch may also catch

 		// situations where a proxy is involved, returning a HTML response.

 		daemonErr = errors.New(strings.TrimSpace(string(body)))

 	}

@@ -74,9 +74,9 @@ func TestSetHostHeader(t *testing.T) {

 	}

 }

-// TestPlainTextError tests the server returning an error in plain text for

-// backwards compatibility with API versions <1.24. All other tests use

-// errors returned as JSON

+// TestPlainTextError tests the server returning an error in plain text.

+// API versions < 1.24 returned plain text errors, but we may encounter

+// other situations where a non-JSON error is returned.

 func TestPlainTextError(t *testing.T) {

 	client, err := NewClientWithOpts(WithMockClient(plainTextErrorMock(http.StatusInternalServerError, "Server error")))

 	assert.NilError(t, err)

@@ -99,11 +99,9 @@ const DummyHost = "api.moby.localhost"

 // This version may be lower than the version of the api library module used.

 const MaxAPIVersion = "1.52"

-// fallbackAPIVersion is the version to fallback to if API-version negotiation

-// fails. This version is the highest version of the API before API-version

-// negotiation was introduced. If negotiation fails (or no API version was

-// included in the API response), we assume the API server uses the most

-// recent version before negotiation was introduced.

+// fallbackAPIVersion is the version to fall back to if API-version negotiation

+// fails. API versions below this version are not supported by the client,

+// and not considered when negotiating.

 const fallbackAPIVersion = "1.24"

 // Ensure that Client always implements APIClient.

@@ -311,8 +309,7 @@ func (cli *Client) ClientVersion() string {

 // If the API server's ping response does not contain an API version, or if the

 // client did not get a successful ping response, it assumes it is connected with

 // an old daemon that does not support API version negotiation, in which case it

-// downgrades to the latest version of the API before version negotiation was

-// added (1.24).

+// downgrades to the lowest supported API version.

 func (cli *Client) NegotiateAPIVersion(ctx context.Context) {

 	if !cli.manualOverride {

 		// Avoid concurrent modification of version-related fields

@@ -337,10 +334,8 @@ func (cli *Client) NegotiateAPIVersion(ctx context.Context) {

 // ([EnvOverrideAPIVersion]) environment variable, or if the client is initialized

 // with a fixed version ([WithVersion]), no negotiation is performed.

 //

-// If the API server's ping response does not contain an API version, we assume

-// we are connected with an old daemon without API version negotiation support,

-// and downgrade to the latest version of the API before version negotiation was

-// added (1.24).

+// If the API server's ping response does not contain an API version, it falls

+// back to the oldest API version supported.

 func (cli *Client) NegotiateAPIVersionPing(pingResponse types.Ping) {

 	if !cli.manualOverride {

 		// Avoid concurrent modification of version-related fields

@@ -355,8 +350,6 @@ func (cli *Client) NegotiateAPIVersionPing(pingResponse types.Ping) {

 // API version from the ping response.

 func (cli *Client) negotiateAPIVersionPing(pingVersion string) {

 	pingVersion = strings.TrimPrefix(pingVersion, "v")

-

-	// default to the latest version before versioning headers existed

 	if pingVersion == "" {

 		pingVersion = fallbackAPIVersion

 	}

@@ -303,9 +303,8 @@ func checkResponseErr(serverResp *http.Response) (retErr error) {

 			daemonErr = errors.New(strings.TrimSpace(errorResponse.Message))

 		}

 	} else {

-		// Fall back to returning the response as-is for API versions < 1.24

-		// that didn't support JSON error responses, and for situations

-		// where a plain text error is returned. This branch may also catch

+		// Fall back to returning the response as-is for situations where a

+		// plain text error is returned. This branch may also catch

 		// situations where a proxy is involved, returning a HTML response.

 		daemonErr = errors.New(strings.TrimSpace(string(body)))

 	}