vLLM keeps hitting 400 context errors with DeepSeek harness; llama.cpp runs 24h+ fine
cviperr33 · reddit · 2026-08-23
Running Qwen3.8-27b on vLLM with DeepSeek Harness (DSH), the user hits constant 400 errors: the model caps at 115K tokens, but 82K prompt + 32K requested output exceeds it. Raising context to 142K and setting 115K in DSH still fails to compress correctly, and Hermes crashes the server near compaction. Meanwhile llama.cpp runs the same model 24h+ without errors. The post includes the full vLLM launch flags (qwen3coder tool parser, prefix caching, speculative decoding), but the author refuses to cap message context at 32K since the model often thinks at length.
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