Troubleshooting Guides
20 InsiderLLM guides in Troubleshooting — practical, tested walkthroughs for running AI locally, sorted by most recently updated.
- Why Is My Local LLM So Slow? A Diagnostic Guide Local LLM running slow? Check GPU vs CPU inference, VRAM offloading, quantization, context length, backend choice, and thermals. Find your fix in 60 seconds.
- CUDA Out of Memory: What It Means and How to Fix It CUDA out of memory means your model doesn't fit in VRAM. Seven fixes ranked by effort — context length, KV cache quantization, model quant, CPU offload — with tool-specific commands for Ollama, llama.cpp, and LM Studio.
- The 8GB VRAM Trap: What 'Runs on 8GB' Actually Means Every local AI tutorial says 'runs on 8GB!' — and technically it does. What they don't tell you about quantization cliffs, tiny context windows, and why a $300 used GPU changes everything.
- Model Formats Explained: GGUF vs GPTQ vs AWQ vs EXL2 GGUF vs GPTQ vs AWQ vs EXL2/EXL3 model formats explained — plus the new FP4 (MXFP4/NVFP4) and Apple's MLX. What each does, which tools run it, and how to choose for your GPU.
- Fix ROCm Not Detecting Your AMD GPU (2026) AMD GPU not detected in ROCm? Check supported GPUs, fix rocminfo errors, HSA_OVERRIDE hack for unsupported cards, and Ollama/llama.cpp ROCm build fixes.
- LM Studio Tips & Tricks: Faster + Features You Miss (2026) Run local LLMs faster in LM Studio with speculative decoding and MLX, plus the API server, GPU offload, and power-user features most people never touch.
- Ollama Troubleshooting Guide: Every Common Problem and Fix GPU not detected? Running at 1/30th speed on CPU? OOM crashes mid-generation? Every common Ollama error with exact diagnostic commands and fixes for Mac, Windows, and Linux. Updated July 2026 for v0.31.x and Qwen 3.5 + 3.6.
- Local AI Troubleshooting Guide: Every Common Problem and Fix Model running 30x slower than expected? Probably on CPU instead of GPU. Fixes for won't-load errors, CUDA crashes, garbled output, and OOM across Ollama and LM Studio.
- Ollama API Connection Refused: Quick Fixes Ollama API returning connection refused? Check if it's running, fix the port, open it to the network, and solve Docker and WSL2 connectivity issues.
- Open WebUI Not Connecting to Ollama? Every Fix Docker networking, wrong OLLAMA_BASE_URL, localhost confusion, WSL2 isolation, missing models, random disconnects. Every Open WebUI + Ollama connection problem with the exact fix.
- Ollama Not Using GPU: Complete Fix Guide (2026) Ollama running on CPU instead of GPU? Diagnose with ollama ps and nvidia-smi, then fix CUDA, ROCm, WSL2, VRAM limits, and the new Ollama Cloud confusion.
- llama.cpp Build Errors: Common Fixes for Every Platform llama.cpp won't build or runs wrong? CMake, CUDA, Gemma 4 thinking-mode, Qwen 3.6 kwargs, num_ctx VRAM overflow. Exact fixes for every platform.
- LLM Running Slow? Two Different Problems, Two Different Fixes Slow local LLM? Separate time-to-first-token from generation speed. Fix prompt processing with batch size and Flash Attention. Fix tok/s with GPU layers, quantization, and context length.
- Why Your Local LLM Is Slow: The num_ctx VRAM Overflow Nobody Warns You About DeepSeek-R1 14B went from 35 tok/s to 4.8 tok/s on the same GPU. The fix was one parameter. How num_ctx silently overflows VRAM and kills inference speed.
- Qwen2.5-VL Not Loading in LM Studio? Fix mmproj and Vision Errors Fix every Qwen2.5-VL error in LM Studio: missing mmproj, 'model type not supported', no eye icon, vision crashes. Exact fixes with file paths.
- Ollama on Mac Not Working? Fix Metal, Memory Pressure, and Slow Performance ollama ps says CPU? Generation crawling at 2 tok/s? macOS killed your model mid-sentence? Every Mac-specific Ollama problem diagnosed and fixed with exact commands.
- Model Outputs Garbage: Debugging Bad Generations Local LLM outputs repetitive loops, gibberish, or wrong answers? Seven causes with exact fixes — from corrupted downloads to wrong chat templates.
- Memory Leak in Long Conversations: Causes and Fixes VRAM climbs with every message until your model crashes? It's probably KV cache growth, not a leak. How to diagnose, monitor, and fix memory issues in local LLMs.
- GGUF File Won't Load: Format and Compatibility Fixes GGUF model won't load? Version mismatch, corrupted download, wrong format, split files, or memory issues. Find your error and fix it in under a minute.
- Context Length Exceeded: What To Do When Your Model Runs Out of Space Model forgetting earlier messages or throwing context errors? How context length works, what happens when it fills, and practical fixes for chat, RAG, and coding.