--- page_id: curated-troubleshooting type: context-page schema_version: 1 template_id: curated-knowledge template_version: template-0.1.0 title: Troubleshooting slug: curated-troubleshooting route: /troubleshooting section: reference access: public summary: Fault-isolation entry point for digital flow, environment, DRC, LVS, timing, and tool failures. status: published asset_base: . home_href: / md_url: /troubleshooting.md toc_enabled: true talk_enabled: false agent_view_enabled: true copy_buttons_enabled: true footer_enabled: true search_indexed: true tags: [wafer-space, knowledge-base, curated] last_updated: 2026-08-19 talk_url: /troubleshooting.talk.md talk_route: /troubleshooting/talk --- # Troubleshooting ## Scope This page is the fault-isolation entry point. It routes a symptom to the smallest useful investigation. Detailed DRC/LVS and tool-crash remedies are on the linked pages. ## First response 1. Preserve the failed run directory, exact command, resolved configuration, first error, logs, report databases, template tag, Nix lock, and PDK/tool versions. This is an inferred evidence set from successful reduced-case and local-versus-CI investigations. [Reduced-case evidence](/evidence/i-information/general/threads/using-gf180mcuocdio-in-librelane#message-1443614636464148552) ([Discord](https://discord.com/channels/1361349522684510449/1443243481744277565/1443614636464148552)) [Environment evidence](/evidence/designing/project-template/threads/only-thing-i-can-think-of-is-the-nix#message-1512740258649870336) ([Discord](https://discord.com/channels/1361349522684510449/1512739634692489366/1512740258649870336)) 2. Decide whether the fault follows the design, the machine, or the pinned environment. A recorded local KLayout XOR failure did not occur in GitHub CI, so the investigation compared locks, tested the vanilla template, and inspected the preceding Magic GDS. [Evidence](/evidence/designing/project-template/threads/only-thing-i-can-think-of-is-the-nix#message-1512912751641628845) ([Discord](https://discord.com/channels/1361349522684510449/1512739634692489366/1512912751641628845)) 3. Reduce the failing object. KLayout was run on one failing cell with the same DRC deck to create a smaller case. [Evidence](/evidence/i-information/general/threads/using-gf180mcuocdio-in-librelane#message-1443614548182568971) ([Discord](https://discord.com/channels/1361349522684510449/1443243481744277565/1443614548182568971)) 4. Do not discard a crash as normal. OpenROAD segfaults were explicitly described as upstream bugs that should be reported with a reproducer. [Evidence](/evidence/i-information/general/threads/using-gf180mcuocdio-in-librelane#message-1443385708302831667) ([Discord](https://discord.com/channels/1361349522684510449/1443243481744277565/1443385708302831667)) ## Symptom routing - **Yosys check failure:** read the first check detail in `yosys-synthesis.log` and `reports/pre_synth_chk.rpt`, then reduce to a Yosys-only case. [Evidence](/evidence/i-information/questions/threads/yosys-check-errors-found#message-1440439686526144552) ([Discord](https://discord.com/channels/1361349522684510449/1440427510159638538/1440439686526144552)) - **Post-route hold failure:** inspect the post-PNR summary and the failing corner's `min.rpt`; then use the ECO procedure and route the inserted cells. [Evidence](/evidence/i-information/questions/threads/failing-hold-checks#message-1445872535160885409) ([Discord](https://discord.com/channels/1361349522684510449/1445866342438932643/1445872535160885409)) [Routing evidence](/evidence/i-information/questions/threads/failing-hold-checks#message-1445910109375959070) ([Discord](https://discord.com/channels/1361349522684510449/1445866342438932643/1445910109375959070)) - **DRC slow or apparently hung:** check CPU, memory, log timestamps, PDK version, and connectivity setup before changing the rule deck. PDK 1.4.1 fixed one connectivity problem and reduced a tested run from hours to about 1.5 hours. [Evidence](/evidence/designing/project-template#message-1446446102734962835) ([Discord](https://discord.com/channels/1361349522684510449/1423348662318272592/1446446102734962835)) - **LVS count or pin mismatch:** inspect `lvs.netgen.rpt`, confirm that layout and Verilog are from the same run, then check LEF labels and hierarchy. [Report evidence](/evidence/designing/project-template/threads/pure-digital-no-hard-macros-no-sram#message-1446665494374646050) ([Discord](https://discord.com/channels/1361349522684510449/1445210755434549288/1446665494374646050)) [Stale-netlist evidence](/evidence/designing/project-template/threads/pure-digital-no-hard-macros-no-sram#message-1446673863537590324) ([Discord](https://discord.com/channels/1361349522684510449/1445210755434549288/1446673863537590324)) - **Magic open-file limit:** use a template/LibreLane version with `locking disable`. The fix shipped in Template 1.5.2 on 2026-06-08. [Evidence](/evidence/designing/project-template#message-1513546884726259844) ([Discord](https://discord.com/channels/1361349522684510449/1423348662318272592/1513546884726259844)) ## Status boundaries - **Obsolete guidance:** `conn_drc false` was a diagnostic bypass for very slow KLayout connectivity construction. It loses connectivity information and can create worst-case false positives. A later PDK fixed the recorded connectivity problem. [Bypass](/evidence/designing/project-template/threads/pure-digital-no-hard-macros-no-sram#message-1445398457929171079) ([Discord](https://discord.com/channels/1361349522684510449/1445210755434549288/1445398457929171079)) [Warning](/evidence/designing/project-template/threads/pure-digital-no-hard-macros-no-sram#message-1445398872594579530) ([Discord](https://discord.com/channels/1361349522684510449/1445210755434549288/1445398872594579530)) [Fix](/evidence/designing/project-template#message-1446446102734962835) ([Discord](https://discord.com/channels/1361349522684510449/1423348662318272592/1446446102734962835)) - **Open question:** A report that a tool is “stuck” is not enough to separate a hang from a slow connectivity or extraction step. Preserve complete logs and resource use before classifying the fault. This is an inference from the multi-hour KLayout case. [Evidence](/evidence/designing/project-template#message-1446446102734962835) ([Discord](https://discord.com/channels/1361349522684510449/1423348662318272592/1446446102734962835)) ## Related pages - [DRC and LVS](/troubleshooting/drc-and-lvs) - [Tool Failures](/troubleshooting/tool-failures) - [RTL, Synthesis, and Simulation](/digital-design/rtl-synthesis-and-simulation) - [Timing and ECO](/digital-design/timing-and-eco) - [Version Management](/librelane-and-tooling/version-management) - [Digital Design](/digital-design) ## Sources - `1443614548182568971` — 2025-11-27T14:48:49.348+00:00 — tnt (@246tnt); `1443614636464148552` — 2025-11-27T14:49:10.396+00:00 — tnt (@246tnt) — reduced single-cell KLayout run. [Evidence 1](/evidence/i-information/general/threads/using-gf180mcuocdio-in-librelane#message-1443614548182568971) ([Discord](https://discord.com/channels/1361349522684510449/1443243481744277565/1443614548182568971)) [Evidence 2](/evidence/i-information/general/threads/using-gf180mcuocdio-in-librelane#message-1443614636464148552) ([Discord](https://discord.com/channels/1361349522684510449/1443243481744277565/1443614636464148552)) - `1512740258649870336` — 2026-06-06T08:49:43.017+00:00 — Leo Moser (mole99) (@mole99); `1512912751641628845` — 2026-06-06T20:15:08.551+00:00 — RebelMike (@rebelmike) — Nix and local-versus-CI diagnosis. [Evidence 1](/evidence/designing/project-template/threads/only-thing-i-can-think-of-is-the-nix#message-1512740258649870336) ([Discord](https://discord.com/channels/1361349522684510449/1512739634692489366/1512740258649870336)) [Evidence 2](/evidence/designing/project-template/threads/only-thing-i-can-think-of-is-the-nix#message-1512912751641628845) ([Discord](https://discord.com/channels/1361349522684510449/1512739634692489366/1512912751641628845)) - `1443385708302831667` — 2025-11-26T23:39:29.669+00:00 — Tim 'mithro' Ansell (@mithro_) — report OpenROAD segfaults upstream. [Evidence](/evidence/i-information/general/threads/using-gf180mcuocdio-in-librelane#message-1443385708302831667) ([Discord](https://discord.com/channels/1361349522684510449/1443243481744277565/1443385708302831667)) - `1440439686526144552` — 2025-11-18T20:33:03.343+00:00 — aedancullen — Yosys check locations. [Evidence](/evidence/i-information/questions/threads/yosys-check-errors-found#message-1440439686526144552) ([Discord](https://discord.com/channels/1361349522684510449/1440427510159638538/1440439686526144552)) - `1445872535160885409` — 2025-12-03T20:21:15.395+00:00 — Lofty (@ravenslofty); `1445910109375959070` — 2025-12-03T22:50:33.786+00:00 — Trevor Peyton (@trev5514) — timing and ECO routing. [Evidence 1](/evidence/i-information/questions/threads/failing-hold-checks#message-1445872535160885409) ([Discord](https://discord.com/channels/1361349522684510449/1445866342438932643/1445872535160885409)) [Evidence 2](/evidence/i-information/questions/threads/failing-hold-checks#message-1445910109375959070) ([Discord](https://discord.com/channels/1361349522684510449/1445866342438932643/1445910109375959070)) - `1446446102734962835` — 2025-12-05T10:20:24.561+00:00 — Leo Moser (mole99) (@mole99) — PDK 1.4.1 KLayout connectivity fix. [Evidence](/evidence/designing/project-template#message-1446446102734962835) ([Discord](https://discord.com/channels/1361349522684510449/1423348662318272592/1446446102734962835)) - `1446665494374646050` — 2025-12-06T00:52:11.604+00:00 — bailey (@bailey8889); `1446673863537590324` — 2025-12-06T01:25:26.968+00:00 — bailey (@bailey8889) — Netgen report and stale netlist. [Evidence 1](/evidence/designing/project-template/threads/pure-digital-no-hard-macros-no-sram#message-1446665494374646050) ([Discord](https://discord.com/channels/1361349522684510449/1445210755434549288/1446665494374646050)) [Evidence 2](/evidence/designing/project-template/threads/pure-digital-no-hard-macros-no-sram#message-1446673863537590324) ([Discord](https://discord.com/channels/1361349522684510449/1445210755434549288/1446673863537590324)) - `1513546884726259844` — 2026-06-08T14:14:57.66+00:00 — Leo Moser (mole99) (@mole99) — Magic file-locking fix. [Evidence](/evidence/designing/project-template#message-1513546884726259844) ([Discord](https://discord.com/channels/1361349522684510449/1423348662318272592/1513546884726259844)) - `1445398457929171079` — 2025-12-02T12:57:26.575+00:00 — Leo Moser (mole99) (@mole99); `1445398872594579530` — 2025-12-02T12:59:05.439+00:00 — Leo Moser (mole99) (@mole99) — `conn_drc false` bypass and warning. [Evidence 1](/evidence/designing/project-template/threads/pure-digital-no-hard-macros-no-sram#message-1445398457929171079) ([Discord](https://discord.com/channels/1361349522684510449/1445210755434549288/1445398457929171079)) [Evidence 2](/evidence/designing/project-template/threads/pure-digital-no-hard-macros-no-sram#message-1445398872594579530) ([Discord](https://discord.com/channels/1361349522684510449/1445210755434549288/1445398872594579530))