# App crashing in Preview mode (Dev) but works fine in Production **URL:** \ **Category:** Workspace\ **Tags:** using-replit\ **Created:** [February 26, 2026, 11:50am UTC](https://replit.discourse.group/t/app-crashing-in-preview-mode-dev-but-works-fine-in-production/9515 "2026-02-26T11:50:20Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![shubhamkuma1024](https://avatars.discourse-cdn.com/v4/letter/s/8e7dd6/32.png) [@shubhamkuma1024](https://replit.discourse.group/u/shubhamkuma1024)\ **Post date:** [February 26, 2026, 11:50am UTC](https://replit.discourse.group/t/app-crashing-in-preview-mode-dev-but-works-fine-in-production/9515/1 "2026-02-26T11:50:20Z")
Hi everyone, I’m facing an issue where my app **crashes in Preview mode in the dev environment** , but the **same build runs fine in production**. - Preview mode crashes immediately / on load - Production deployment works without any issues - Environment variables and configs seem correct Has anyone faced something similar on Replit? Any ideas on what could cause Preview mode to behave differently from production? Thanks in advance! ---
**Author:** ![soullennon41](https://yyz2.discourse-cdn.com/flex010/user_avatar/replit.discourse.group/soullennon41/32/3086_2.png) [@soullennon41](https://replit.discourse.group/u/soullennon41)\ **Post date:** [February 26, 2026, 11:54am UTC](https://replit.discourse.group/t/app-crashing-in-preview-mode-dev-but-works-fine-in-production/9515/2 "2026-02-26T11:54:14Z")
Yes I have the same problem and have emailed Replit with the details. Hope they find a solution soon. (Just hope they can refund the part where I tried to use the agent to debug) ---
**Author:** ![marcinmaciejcie](https://avatars.discourse-cdn.com/v4/letter/m/db5fbb/32.png) [@marcinmaciejcie](https://replit.discourse.group/u/marcinmaciejcie)\ **Post date:** [February 26, 2026, 11:58am UTC](https://replit.discourse.group/t/app-crashing-in-preview-mode-dev-but-works-fine-in-production/9515/3 "2026-02-26T11:58:22Z")
The same issue here [Each of my apps is crashing 30 seconds after opening - #12](https://replit.discourse.group/t/each-of-my-apps-is-crashing-30-seconds-after-opening/9504/12) ---
**Author:** ![shubhamkuma1024](https://avatars.discourse-cdn.com/v4/letter/s/8e7dd6/32.png) [@shubhamkuma1024](https://replit.discourse.group/u/shubhamkuma1024)\ **Post date:** [February 26, 2026, 12:17pm UTC](https://replit.discourse.group/t/app-crashing-in-preview-mode-dev-but-works-fine-in-production/9515/4 "2026-02-26T12:17:33Z")
please let me know, if they come up with any solution or reply ton your email ---
**Author:** ![justinsertcoin](https://avatars.discourse-cdn.com/v4/letter/j/a6a055/32.png) [@justinsertcoin](https://replit.discourse.group/u/justinsertcoin)\ **Post date:** [February 26, 2026, 12:25pm UTC](https://replit.discourse.group/t/app-crashing-in-preview-mode-dev-but-works-fine-in-production/9515/5 "2026-02-26T12:25:01Z")
Came here to say the same. My agent ran for an hour and came back with nothing helpful. @soullennon41 , I hope so too. I didn’t actually try any of the other apps. I just went and tested one other app, and the same happened. Glad (in a way) that this is more of a community issue than just my apps. ---
**Author:** ![vikocloud](https://avatars.discourse-cdn.com/v4/letter/v/94ad74/32.png) [@vikocloud](https://replit.discourse.group/u/vikocloud)\ **Post date:** [February 26, 2026, 12:42pm UTC](https://replit.discourse.group/t/app-crashing-in-preview-mode-dev-but-works-fine-in-production/9515/6 "2026-02-26T12:42:00Z")
this is horrible, the preview dies after a couple of minutes without any console error, however in my case only applies to fastapi builds, while running the same build in bash, the server is running smoothly in the bg, so basically the only affected component is the preview. i was thinking that i overcomuputed the ide limit, but even a 15 lines minimal pseudocode dies in preview. anybody has the same experience? ---
**Author:** ![FranciscoCM](https://yyz2.discourse-cdn.com/flex010/user_avatar/replit.discourse.group/franciscocm/32/1693_2.png) [@FranciscoCM](https://replit.discourse.group/u/FranciscoCM)\ **Post date:** [February 26, 2026, 11:28pm UTC](https://replit.discourse.group/t/app-crashing-in-preview-mode-dev-but-works-fine-in-production/9515/8 "2026-02-26T23:28:31Z")
Hello everyone 👋 Apologize that you are dealing with some issues here but am happy to update that [this has been resolved.](https://x.com/ReplitSupport/status/2027108273783280079) As @RocketMan mentioned if you are still having issues please create a support ticket and feel free to share the # in this thread. ---
**Author:** ![pdstransportado](https://avatars.discourse-cdn.com/v4/letter/p/e19b73/32.png) [@pdstransportado](https://replit.discourse.group/u/pdstransportado)\ **Post date:** [March 15, 2026, 1:37am UTC](https://replit.discourse.group/t/app-crashing-in-preview-mode-dev-but-works-fine-in-production/9515/9 "2026-03-15T01:37:25Z")
Estou enfrentando o mesmo problema. Após utilizar mais de 100 prompts durante vários dias o agente chegou a conclusão que não consegue resolver: “Ok, não posso editar `.replit` e o workflow fica parando. Vou investigar de forma diferente — por que o workflow continua parando sozinho, e se o Vite está compilando sem erros. O problema está na configuração de infraestrutura do Replit. Seu arquivo `.replit` (que eu NÃO posso editar, o sistema bloqueia) tem uma entrada `localPort = 80` como primeira porta“. ---
**Author:** ![pdstransportado](https://avatars.discourse-cdn.com/v4/letter/p/e19b73/32.png) [@pdstransportado](https://replit.discourse.group/u/pdstransportado)\ **Post date:** [March 15, 2026, 1:43am UTC](https://replit.discourse.group/t/app-crashing-in-preview-mode-dev-but-works-fine-in-production/9515/10 "2026-03-15T01:43:00Z")
Apesar de ter encaminhado email para o suporte, ainda não recebi o retorno referente a solicitação abaixo: Meu projeto tem o preview do workspace preso em “carregando” há mais de uma semana. Meus outros 2 projetos funcionam normalmente. O problema identificado: meu arquivo `.replit` tem uma entrada `localPort = 80, externalPort = 80` como primeira porta, mas o servidor roda na porta 5000 (`waitForPort = 5000`). O Replit está tentando rotear o webview para porta 80 em vez de 5000. O Agent não consegue corrigir isso porque editar `.replit` é bloqueado pelo sistema. ID do Repl: `3629898b-c5af-4a1f-a9fb-dec6ee28e970` Solicitação: remover a entrada `localPort = 80, externalPort = 80` do meu `.replit`, deixando apenas `localPort = 5000, externalPort = 5000`. ---
**Author:** ![pdstransportado](https://avatars.discourse-cdn.com/v4/letter/p/e19b73/32.png) [@pdstransportado](https://replit.discourse.group/u/pdstransportado)\ **Post date:** [March 16, 2026, 1:26am UTC](https://replit.discourse.group/t/app-crashing-in-preview-mode-dev-but-works-fine-in-production/9515/11 "2026-03-16T01:26:30Z")
O suporte me deu retorno e solicitou que removesse manualmente a porta 80. Segui os passos informado pelo suporte e deu certo!