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POHttpServerUtility.UrlTokenDecode fails "sometimes" (Invalid length for a Base-64 char array.)
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  1. POHttpServerUtility.UrlTokenDecode fails "sometimes" (Invalid length for a Base-64 char array.)
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    copied!<p>We have an <code>IHttpHandler</code> for stylesheets and add a <code>&lt;link/&gt;</code> tag to the page like this:</p> <pre><code>HtmlGenericControl link = new HtmlGenericControl("link"); link.Attributes.Add("rel", "stylesheet"); link.Attributes.Add("href", "stylesheet.axd?d=" + HttpServerUtility.UrlTokenEncode(token)); head.Controls.Add(link); </code></pre> <p>In the <code>stylesheet.axd</code> handler, we <code>UrlTokenDecode</code> the <code>d</code> query string parameter like this:</p> <pre><code>var token = HttpServerUtility.UrlTokenDecode(Request.QueryString["d"]); </code></pre> <p>This works most of the time but every now and then we find one of the following two exceptions in our log:</p> <pre><code>[FormatException: Invalid character in a Base-64 string.] System.Convert.FromBase64CharArray(Char[] inArray, Int32 offset, Int32 length) System.Web.HttpServerUtility.UrlTokenDecode(String input) ... [FormatException: Invalid length for a Base-64 char array.] System.Convert.FromBase64CharArray(Char[] inArray, Int32 offset, Int32 length) System.Web.HttpServerUtility.UrlTokenDecode(String input) System.Web.HttpServerUtilityWrapper.UrlTokenDecode(String input) ... </code></pre> <p>Any ideas what would cause this phenomenon?</p> <p>Remarks:</p> <ul> <li>the resulting URL is &lt; 1500, so below any known URL limits (e.g. IE: 2083)</li> <li>seems to be independent of user agent (we have these exceptions for IE6,7,8, FF &amp; Chrome)</li> <li>our (unconfirmed) suspicions include AntiVirus products, HTTP proxies, browser addons</li> <li>found <a href="https://stackoverflow.com/questions/858761/what-causing-this-invalid-length-for-a-base-64-char-array">this</a> remotely related question, but it's about a viewstate issue</li> </ul>
 

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