A Study of JNJ-77242113 for the Treatment of Participants With Generalized Pustular Psoriasis or Erythrodermic Psoriasis

The purpose of this study is to evaluate how effective JNJ-77242113 is in participants with generalized pustular psoriasis (GPP) or erythrodermic psoriasis (EP).

Inclusion Criteria: * The study participant has a diagnosis of generalized pustular psoriasis (GPP) or erythrodermic psoriasis (EP) at screening. For GPP, a diagnosis must be classified based on the criteria for diagnosis of GPP by the Japanese Dermatological Association (JDA); for EP, has a history of plaque-type psoriasis. In addition, has an involved body surface area (BSA) of lesion greater than or equal to (\>=) 80 percent (%) at baseline * Candidate for phototherapy or systemic treatment for psoriasis (either naive or history of previous treatment) * A female participant of childbearing potential must have a negative highly sensitive serum pregnancy test (beta-human chorionic gonadotropin \[beta-hCG\]) at screening and have a negative urine pregnancy test at Week 0 prior to administration of study intervention * A male participant must agree not to plan to father a child while enrolled in this study or within 90 days after the last dose of study intervention * A male participant must agree not to donate sperm for the purpose of reproduction during the study and for a minimum of 90 days after receiving the last dose of study intervention Exclusion Criteria: * The study participant has a total score of JDA severity index for GPP \>=14 at baseline if participants have a diagnosis of GPP * The study participant has a differential diagnosis of the erythroderma (for example, erythroderma caused by lymphoma or drug eruption) other than EP * The study participant has a history of or current diagnosis or signs or symptoms of severe, progressive, or uncontrolled liver, renal; cardiac, vascular, pulmonary, gastrointestinal, endocrine, neurologic, hematologic, rheumatologic, psychiatric, or metabolic disturbances * The study participant has a history of amyloidosis * Known allergies, hypersensitivity, or intolerance to JNJ-77242113 or its excipients * The study participant who doesn't meet the criteria of prior/current concomitant therapy and/or history/conditions of infections