This is likely a temporary portal or validation issue, not something you did wrong. When candidates try to change category from GEN to OBC-NCL during the GATE correction window, the system checks required fields and sometimes a supporting certificate or fee is needed. If any required data or document is missing, or the server is busy, the portal can show Something went wrong, please try again. Explain to them that first they should log into the GATE portal, open the Correction tab and confirm which fields are editable and whether a payment or document upload is required for category change. Tell them to clear browser cache or try a different browser/device and retry. If the error persists, advise contacting GATE support or the zonal office with a screenshot and timing of the error so officials can check server logs.