I got error every time when I try to enter the game or create own game

java.util.concurrent.CompletionException: error="access_denied", error_description="Error requesting access token."
at org.springframework.aop.interceptor.AsyncExecutionAspectSupport.lambda$doSubmit$3(AsyncExecutionAspectSupport.java:279)
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1764)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: error="access_denied", error_description="Error requesting access token."
at org.springframework.security.oauth2.client.token.OAuth2AccessTokenSupport.retrieveToken(OAuth2AccessTokenSupport.java:149)
at org.springframework.security.oauth2.client.token.grant.password.ResourceOwnerPasswordAccessTokenProvider.obtainAccessToken(ResourceOwnerPasswordAccessTokenProvider.java:52)
at org.springframework.security.oauth2.client.token.AccessTokenProviderChain.obtainNewAccessTokenInternal(AccessTokenProviderChain.java:152)
at org.springframework.security.oauth2.client.token.AccessTokenProviderChain.obtainAccessToken(AccessTokenProviderChain.java:125)
at org.springframework.security.oauth2.client.OAuth2RestTemplate.acquireAccessToken(OAuth2RestTemplate.java:225)
at org.springframework.security.oauth2.client.OAuth2RestTemplate.getAccessToken(OAuth2RestTemplate.java:177)
at org.springframework.security.oauth2.client.OAuth2RestTemplate.createRequest(OAuth2RestTemplate.java:109)
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:771)
at org.springframework.security.oauth2.client.OAuth2RestTemplate.doExecute(OAuth2RestTemplate.java:132)
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:710)
at org.springframework.web.client.RestTemplate.getForObject(RestTemplate.java:333)
at com.faforever.client.api.FafApiAccessorImpl.getPage(FafApiAccessorImpl.java:752)
at com.faforever.client.api.FafApiAccessorImpl.getPage(FafApiAccessorImpl.java:721)
at com.faforever.client.api.FafApiAccessorImpl.getMany(FafApiAccessorImpl.java:711)
at com.faforever.client.api.FafApiAccessorImpl.getFeaturedMods(FafApiAccessorImpl.java:204)
at jdk.internal.reflect.GeneratedMethodAccessor103.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:198)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
at org.springframework.cache.interceptor.CacheInterceptor.lambda$invoke$0(CacheInterceptor.java:54)
at org.springframework.cache.interceptor.CacheAspectSupport.invokeOperation(CacheAspectSupport.java:366)
at org.springframework.cache.interceptor.CacheAspectSupport.lambda$handleSynchronizedGet$1(CacheAspectSupport.java:447)
at org.springframework.cache.caffeine.CaffeineCache$LoadFunction.apply(CaffeineCache.java:168)
at com.github.benmanes.caffeine.cache.UnboundedLocalCache.lambda$computeIfAbsent$2(UnboundedLocalCache.java:238)
at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1708)
at com.github.benmanes.caffeine.cache.UnboundedLocalCache.computeIfAbsent(UnboundedLocalCache.java:234)
at com.github.benmanes.caffeine.cache.LocalCache.computeIfAbsent(LocalCache.java:108)
at com.github.benmanes.caffeine.cache.LocalManualCache.get(LocalManualCache.java:62)
at org.springframework.cache.caffeine.CaffeineCache.get(CaffeineCache.java:90)
at org.springframework.cache.interceptor.CacheAspectSupport.handleSynchronizedGet(CacheAspectSupport.java:442)
at org.springframework.cache.interceptor.CacheAspectSupport.execute(CacheAspectSupport.java:382)
at org.springframework.cache.interceptor.CacheAspectSupport.execute(CacheAspectSupport.java:345)
at org.springframework.cache.interceptor.CacheInterceptor.invoke(CacheInterceptor.java:64)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:215)
at com.sun.proxy.$Proxy80.getFeaturedMods(Unknown Source)
at com.faforever.client.remote.FafService.getFeaturedMods(FafService.java:281)
at com.faforever.client.remote.FafService$$FastClassBySpringCGLIB$$6c91c77e.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:771)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:749)
at org.springframework.aop.interceptor.AsyncExecutionInterceptor.lambda$invoke$0(AsyncExecutionInterceptor.java:115)
at org.springframework.aop.interceptor.AsyncExecutionAspectSupport.lambda$doSubmit$3(AsyncExecutionAspectSupport.java:276)
... 4 more
Caused by: org.springframework.web.client.ResourceAccessException: I/O error on POST request for "https://api.faforever.com/oauth/token": PKIX path validation failed: java.security.cert.CertPathValidatorException: validity check failed; nested exception is javax.net.ssl.SSLHandshakeException: PKIX path validation failed: java.security.cert.CertPathValidatorException: validity check failed
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:784)
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:731)
at org.springframework.security.oauth2.client.token.OAuth2AccessTokenSupport.retrieveToken(OAuth2AccessTokenSupport.java:141)
... 49 more
Caused by: javax.net.ssl.SSLHandshakeException: PKIX path validation failed: java.security.cert.CertPathValidatorException: validity check failed
at java.base/sun.security.ssl.Alert.createSSLException(Alert.java:131)
at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:369)
at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:312)
at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:307)
at java.base/sun.security.ssl.CertificateMessage$T13CertificateConsumer.checkServerCerts(CertificateMessage.java:1357)
at java.base/sun.security.ssl.CertificateMessage$T13CertificateConsumer.onConsumeCertificate(CertificateMessage.java:1232)
at java.base/sun.security.ssl.CertificateMessage$T13CertificateConsumer.consume(CertificateMessage.java:1175)
at java.base/sun.security.ssl.SSLHandshake.consume(SSLHandshake.java:396)
at java.base/sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:480)
at java.base/sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:458)
at java.base/sun.security.ssl.TransportContext.dispatch(TransportContext.java:199)
at java.base/sun.security.ssl.SSLTransport.decode(SSLTransport.java:171)
at java.base/sun.security.ssl.SSLSocketImpl.decode(SSLSocketImpl.java:1488)
at java.base/sun.security.ssl.SSLSocketImpl.readHandshakeRecord(SSLSocketImpl.java:1394)
at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:441)
at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:412)
at java.base/sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:567)
at java.base/sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:183)
at java.base/sun.net.www.protocol.https.HttpsURLConnectionImpl.connect(HttpsURLConnectionImpl.java:142)
at org.springframework.http.client.SimpleBufferingClientHttpRequest.executeInternal(SimpleBufferingClientHttpRequest.java:76)
at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48)
at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:66)
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:775)
... 51 more
Caused by: sun.security.validator.ValidatorException: PKIX path validation failed: java.security.cert.CertPathValidatorException: validity check failed
at java.base/sun.security.validator.PKIXValidator.doValidate(PKIXValidator.java:369)
at java.base/sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:275)
at java.base/sun.security.validator.Validator.validate(Validator.java:264)
at java.base/sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:231)
at java.base/sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:132)
at java.base/sun.security.ssl.CertificateMessage$T13CertificateConsumer.checkServerCerts(CertificateMessage.java:1341)
... 69 more
Caused by: java.security.cert.CertPathValidatorException: validity check failed
at java.base/sun.security.provider.certpath.PKIXMasterCertPathValidator.validate(PKIXMasterCertPathValidator.java:135)
at java.base/sun.security.provider.certpath.PKIXCertPathValidator.validate(PKIXCertPathValidator.java:237)
at java.base/sun.security.provider.certpath.PKIXCertPathValidator.validate(PKIXCertPathValidator.java:145)
at java.base/sun.security.provider.certpath.PKIXCertPathValidator.engineValidate(PKIXCertPathValidator.java:84)
at java.base/java.security.cert.CertPathValidator.validate(CertPathValidator.java:309)
at java.base/sun.security.validator.PKIXValidator.doValidate(PKIXValidator.java:364)
... 74 more
Caused by: java.security.cert.CertificateNotYetValidException: NotBefore: Mon Mar 01 22:17:37 EET 2021
at java.base/sun.security.x509.CertificateValidity.valid(CertificateValidity.java:273)
at java.base/sun.security.x509.X509CertImpl.checkValidity(X509CertImpl.java:665)
at java.base/sun.security.provider.certpath.BasicChecker.verifyValidity(BasicChecker.java:190)
at java.base/sun.security.provider.certpath.BasicChecker.check(BasicChecker.java:144)
at java.base/sun.security.provider.certpath.PKIXMasterCertPathValidator.validate(PKIXMasterCertPathValidator.java:125)
... 79 more

Our Let's encrypt certificate gets renewed every 30 days (that's how Let's encrypt works). Either you exactly hit the time when the old certificate was replaced or you have a tiny issue that the time it starts to be valid from is not correctly compared to your timezones time.
Nevertheless. Please retry (close and reopen the client) in an hour, in 2 hours, in a day. This should fix itself.

"Nerds have a really complicated relationship with change: Change is awesome when WE'RE the ones doing it. As soon as change is coming from outside of us it becomes untrustworthy and it threatens what we think of is the familiar."
ā€“ Benno Rice

Thanks
Will wait

Issue resolved
You are right I had troubles with timezone