Introduction

net::ERR_CACHE_MISS in Android WebView usually appears when the WebView tries to revisit or reload a request that cannot be satisfied from its current state. In practice, this often happens after POST-based form submissions, back navigation to a page that expects resubmission, or when developers misunderstand what WebView caching can and cannot restore.

Despite the message text, the root problem is often navigation semantics rather than a damaged cache. Treat it first as a request-lifecycle issue, then as a caching issue only if the page genuinely depends on local resource caching.

Why It Happens

WebView is built on Chromium behavior. When a page was loaded through a POST request, navigating back or refreshing may require the original request body again. If the browser state does not simply replay that body, WebView may surface net::ERR_CACHE_MISS.

This means the error often appears in scenarios like:

• Submitting a form and pressing Back.
• Refreshing a page that was produced by POST.
• Returning to a page whose resources or navigation state were never cacheable.

If you only respond by calling clearCache(true), you usually make the symptom worse or at least fail to address the cause.

A Sensible WebView Setup

Start with a normal WebView configuration and explicit navigation handling.

1import android.annotation.SuppressLint
2import android.os.Bundle
3import android.webkit.WebSettings
4import android.webkit.WebView
5import android.webkit.WebViewClient
6import androidx.appcompat.app.AppCompatActivity
7
8class MainActivity : AppCompatActivity() {
9    private lateinit var webView: WebView
10
11    @SuppressLint("SetJavaScriptEnabled")
12    override fun onCreate(savedInstanceState: Bundle?) {
13        super.onCreate(savedInstanceState)
14        webView = WebView(this)
15        setContentView(webView)
16
17        webView.settings.javaScriptEnabled = true
18        webView.settings.cacheMode = WebSettings.LOAD_DEFAULT
19        webView.webViewClient = WebViewClient()
20
21        webView.loadUrl("https://example.com")
22    }
23
24    override fun onBackPressed() {
25        if (webView.canGoBack()) {
26            webView.goBack()
27        } else {
28            super.onBackPressed()
29        }
30    }
31}

This does not “fix” POST resubmission by itself, but it gives you predictable in-app navigation instead of bouncing between app and system browser behavior.

The Real Fix: Avoid POST-Back Traps

If you control the web content, the strongest fix is usually the Post/Redirect/Get pattern.

The flow is:

1. Client submits a POST.
2. Server processes it.
3. Server responds with a redirect.
4. WebView lands on a GET URL that is safe to refresh and revisit.

That removes the resubmission problem at the source. A GET result page can be revisited from history much more safely than a raw POST response page.

If you do not control the server, you can still reduce confusion by handling form flows carefully and avoiding automatic reloads after submission.

When Cache Settings Matter

Cache configuration matters when the issue is truly missing local resources rather than POST navigation. For example, offline content, static assets, or aggressively no-cache server headers can affect whether a revisited page can be reconstructed.

Even then, WebView cache settings are not magic. If the origin sends Cache-Control: no-store, Chromium will not keep that response simply because your app wants it cached.

For pages you control, correct HTTP caching headers are more important than random client-side cache toggles.

Common Pitfalls

A common mistake is assuming net::ERR_CACHE_MISS means “turn cache on harder.” In many cases the request is not cacheable, especially after POST.

Another issue is repeatedly calling reload() after form submission. That can force the WebView into a resubmission path that triggers the same error again.

Developers also sometimes clear the cache during troubleshooting and then wonder why revisits became less reliable. Cache clearing is not a repair mechanism for request-history problems.

Finally, if the WebView is part of a login or payment flow, be careful with back navigation. Some pages are intentionally non-cacheable or non-repeatable for security reasons.

Summary

• 'net::ERR_CACHE_MISS often reflects POST resubmission or navigation-state issues, not just broken caching.'
• The most robust fix is usually Post/Redirect/Get on the server side.
• Handle WebView back navigation explicitly and avoid unnecessary reloads.
• Cache settings help only when the underlying responses are actually cacheable.
• Do not treat clearCache(true) as the default solution for this error.