您好，退款是需要证书，证书校验异常可以首页搜索证书错误关键字，获取解决方法：https://developers.weixin.qq.com/community/develop/doc/0000c4d41540000797489798450800?highLine=%25E8%25AF%2581%25E4%25B9%25A6%25E9%2594%2599%25E8%25AF%25AF

检查证书是否过期，证书路径是否设置为绝对路径

如果还没有解决您的问题，可以前往V3文档：https://pay.weixin.qq.com/wiki/doc/apiv3/wxpay/pages/index.shtml  点击右下角“技术咨询”实时寻求技术帮助。

问题解决了么

证书路径换成相对路径试下

证书是刚下载的，没过期；另外证书路径是绝对路径，已经检测到证书了，但是在发起退款时就出现上述错误，链接超时:

Caused by: java.net.ConnectException: Failed to connect to api.mch.weixin.qq.com/240e:e1:a900:50:0:0:0:4a:443

        at okhttp3.internal.connection.RealConnection.connectSocket(RealConnection.kt:268)

        at okhttp3.internal.connection.RealConnection.connect(RealConnection.kt:180)

        at okhttp3.internal.connection.ExchangeFinder.findConnection(ExchangeFinder.kt:238)

        at okhttp3.internal.connection.ExchangeFinder.findHealthyConnection(ExchangeFinder.kt:111)

        at okhttp3.internal.connection.ExchangeFinder.find(ExchangeFinder.kt:79)

        at okhttp3.internal.connection.Transmitter.newExchange$okhttp(Transmitter.kt:163)

        at okhttp3.internal.connection.ConnectInterceptor.intercept(ConnectInterceptor.kt:35)

        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:112)

        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:87)

        at okhttp3.internal.cache.CacheInterceptor.intercept(CacheInterceptor.kt:82)

        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:112)

        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:87)

        at okhttp3.internal.http.BridgeInterceptor.intercept(BridgeInterceptor.kt:84)

        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:112)

        at okhttp3.internal.http.RetryAndFollowUpInterceptor.intercept(RetryAndFollowUpInterceptor.kt:71)

        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:112)

        at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:87)

        at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.kt:194)

        at okhttp3.RealCall.execute(RealCall.kt:67)

        at com.jfinal.weixin.sdk.utils.HttpUtils$OkHttp3Delegate.postSSL(HttpUtils.java:366)

        ... 100 more

Caused by: java.net.ConnectException: Network is unreachable (connect failed)

        at java.net.PlainSocketImpl.socketConnect(Native Method)

        at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:476)

        at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:218)

        at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:200)

        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:394)

        at java.net.Socket.connect(Socket.java:606)

        at okhttp3.internal.platform.Platform.connectSocket(Platform.kt:117)

        at okhttp3.internal.connection.RealConnection.connectSocket(RealConnection.kt:266)