See https://github.com/spring-projects/spring-boot/issues/28912 for original issue. It looks like trying to read the request body with an H2C-upgraded request fails with an NPE, while this doesn't fail with H2C prior-knowledge or HTTP 1.1. Here is the stacktrace: java.lang.NullPointerException: Cannot invoke "org.apache.coyote.InputBuffer.doRead(org.apache.tomcat.util.net.ApplicationBufferHandler)" because "this.inputBuffer" is null at org.apache.coyote.Request.doRead(Request.java:640) at org.apache.catalina.connector.InputBuffer.realReadBytes(InputBuffer.java:317) at org.apache.catalina.connector.InputBuffer.checkByteBufferEof(InputBuffer.java:600) at org.apache.catalina.connector.InputBuffer.read(InputBuffer.java:340) at org.apache.catalina.connector.CoyoteInputStream.read(CoyoteInputStream.java:132) at java.base/java.io.InputStream.readNBytes(InputStream.java:409) at java.base/java.io.InputStream.readAllBytes(InputStream.java:346) at h2c.H2cServlet.doGet(H2cServlet.java:18) at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:540) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) at org.apache.coyote.http2.StreamProcessor.service(StreamProcessor.java:413) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) at org.apache.coyote.http2.StreamProcessor.process(StreamProcessor.java:74) at org.apache.coyote.http2.StreamRunnable.run(StreamRunnable.java:35) at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.base/java.lang.Thread.run(Thread.java:833) A sample application can be found here: https://github.com/bclozel/h2c-tomcat
Thanks for the report. There are a couple of TODOs for support for request bodies during HTTP/1.1 upgrade in the code. The NPE is caused by the current lack of support. I have a patch for this. Just need to do a little more testing.
Fixed in: - 10.1.x for 10.1.0-M9 onwards - 10.0.x for 10.0.15 onwards - 9.0.x for 9.0.57 onwards - 8.5.x for 8.5.74 onwards