Cannot authenticate client

Whenever I try to log on to a premium server the game says that the authentication servers are down. I know that the servers were on when I tried, so it must be a local issue. There were no problems with the game before, I have not edited any file. 
Few weeks ago my launcher didn't let me log in because it thought that the servers were offline. I've managed to fix that issue by switching to an old version of the staging launcher, which seems to be working fine. 
And since then, I can't log in to any premium server.

I've looked into the log file and it said that it couldn't find the SSL certificate. I tried adding it but it didn't solve the problem. 

 PS: I couldn't attach the log file (Jira could not attach the file as there was a missing token. Please try attaching the file again.) so I will just paste the error here:

 

[0424/214216:INFO:GameCallbacks.cpp(199)] game/com.mojang.authlib.yggdrasil.YggdrasilMinecraftSessionService (Server-Worker-6) warn Couldn't look up profile properties for com.mojang.authlib.GameProfile@5080de1e[id=701182c1-c0a2-3739-b896-ae559f7cd921,name=tibetiroka,properties={},legacy=false][0424/214216:INFO:GameCallbacks.cpp(199)] game/com.mojang.authlib.yggdrasil.YggdrasilMinecraftSessionService (Server-Worker-6) warn Couldn't look up profile properties for com.mojang.authlib.GameProfile@5080de1e[id=701182c1-c0a2-3739-b896-ae559f7cd921,name=tibetiroka,properties={},legacy=false]com.mojang.authlib.exceptions.AuthenticationUnavailableException: Cannot contact authentication server at com.mojang.authlib.yggdrasil.YggdrasilAuthenticationService.makeRequest(YggdrasilAuthenticationService.java:85) at com.mojang.authlib.yggdrasil.YggdrasilMinecraftSessionService.fillGameProfile(YggdrasilMinecraftSessionService.java:180) at com.mojang.authlib.yggdrasil.YggdrasilMinecraftSessionService.fillProfileProperties(YggdrasilMinecraftSessionService.java:173) at eaz.a(SourceFile:94) at eaz$$Lambda$2442/316471914.run(Unknown Source) at java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1402) at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289) at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056) at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1689) at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)Caused by: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target at sun.security.ssl.Alerts.getSSLException(Alerts.java:192) at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1949) at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:302) at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:296) at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1497) at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:212) at sun.security.ssl.Handshaker.processLoop(Handshaker.java:979) at sun.security.ssl.Handshaker.process_record(Handshaker.java:914) at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1062) at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1375) at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1403) at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1387) at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:563) at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185) at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1512) at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1440) at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:254) at com.mojang.authlib.HttpAuthenticationService.performGetRequest(HttpAuthenticationService.java:130) at com.mojang.authlib.yggdrasil.YggdrasilAuthenticationService.makeRequest(YggdrasilAuthenticationService.java:66) ... 9 moreCaused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:387) at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:292) at sun.security.validator.Validator.validate(Validator.java:260) at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:324) at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:229) at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:124) at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1479) ... 23 moreCaused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target at sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:145) at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:131) at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:280) at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:382) ... 29 more