Android webView PORT request failing with ERR_HTTP_RESPONSE_CODE_FAILURE for the first time

Android webview POST request is failing with err_http_response_code_failure error but only for the first time. It works fine in all the subsequent retries. Not sure why it fails only for the first time after app launch. Any ideas? I have tried overriding onReceivedError but its not getting called.

    AndroidView(
        modifier = Modifier.fillMaxSize(),
        factory = { context ->
        WebView(context).apply {
            settings.javaScriptEnabled = true
            settings.domStorageEnabled = true
            settings.loadWithOverviewMode = true

            val myWebViewClient = object: WebViewClient() {

                override fun onReceivedError(view: WebView?, request: WebResourceRequest, error: WebResourceError) {
                    showLoadingScreen = false
                    super.onReceivedError(view, request, error)
                }
            }

            webViewClient = myWebViewClient

            postUrl(url, body.toByteArray())
        }
    }, update = {
        it.layoutParams = ViewGroup.LayoutParams(
            ViewGroup.LayoutParams.MATCH_PARENT,
            ViewGroup.LayoutParams.MATCH_PARENT
        ) }
    )