WD search_api_solr: An error occurred while indexing: '400' Status

WD search_api_solr: An error occurred while indexing: '400' Status: Bad Request.

HTTP Status 500 - Error handling 'reload' action org.apache.solr.common.SolrException: Error handling 'reload' action at org.apache.solr.handler.admin.CoreAdminHandler.handleReloadAction(CoreAdminHandler.java:489) at org.apache.solr.handler.admin.CoreAdminHandler.handleRequestBody(CoreAdminHandler.java:146) at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:129) at org.apache.solr.servlet.SolrDispatchFilter.handleAdminRequest(SolrDispatchFilter.java:318) at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:187) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1001) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:636) Caused by: java.lang.RuntimeException: Can't find resource 'mapping-ISOLatin1Accent.txt' in classpath or 'solr/core0/conf/', cwd=/opt at org.apache.solr.core.SolrResourceLoader.openResource(SolrResourceLoader.java:273) at org.apache.solr.core.SolrResourceLoader.getLines(SolrResourceLoader.java:318) at org.apache.solr.core.SolrResourceLoader.getLines(SolrResourceLoader.java:292) at org.apache.solr.analysis.MappingCharFilterFactory.inform(MappingCharFilterFactory.java:68) at org.apache.solr.core.SolrResourceLoader.inform(SolrResourceLoader.java:551) at org.apache.solr.schema.IndexSchema.(IndexSchema.java:124) at org.apache.solr.core.CoreContainer.create(CoreContainer.java:481) at org.apache.solr.core.CoreContainer.reload(CoreContainer.java:548) at org.apache.solr.handler.admin.CoreAdminHandler.handleReloadAction(CoreAdminHandler.java:486) ... 20 more