Add troubleshooting doc (#856)

docs/en/troubleshooting.md

@@ -0,0 +1,13 @@
+# Troubleshooting
+
+This page lists some common errors and tips for fixing them.
+
+## CUDA error: an illegal memory access was encountered
+This error may be due to kernel errors or out-of-memory issues.
+- If it is a kernel error, it is not easy to fix.
+- If it is out-of-memory, sometimes it will report this error instead of "Out-of-memory." In this case, try setting a smaller value for `--mem-fraction-static`. The default value of `--mem-fraction-static` is around 0.8 - 0.9. https://github.com/sgl-project/sglang/blob/1edd4e07d6ad52f4f63e7f6beaa5987c1e1cf621/python/sglang/srt/server_args.py#L92-L102
+
+## The server hangs
+If the server hangs, try disabling some optimizations when launching the server.
+- Add `--disable-cuda-graph`.
+- Add `--disable-flashinfer-sampling`.