; applicability (1) Effective date The amendments made by this section shall take effect on October 1, 2019. (2) Invalidity of certain petitions and applications (A) In general No person may file, and the Secretary of Homeland Security and the Secretary of State may not accept, adjudicate, or approve any petition under section 204 of the Immigration and Nationality Act ( 8 U.S.C. 1154 ) filed on or after the date of enactment of this Act seeking classification of an alien under section 203(a)(3) or (4) of such Act ( 8 U.S.C. 1153(a) ). Any application for adjustment of status or an immigrant visa based on such a petition shall be invalid. (B) Pending petitions Neither the Secretary of Homeland Security nor the Secretary of State may adjudicate or approve any petition under section 204 of the Immigration and Nationality Act ( 8 U.S.C. 1154 ) pending as of the date of enactment of this Act seeking classification of an alien under section 203(a)(3) or (4) of such Act ( 8 U.S.C. 1153(a) ). Any application for adjustment of status or an immigrant visa based on such a petition shall be invalid. (3) Applicability to waitlisted applicants An alien with regard to whom a petition or application for status under paragraph (3) or (4) of section 203(a) of the Immigration and Nationality Act ( 8 U.S.C. 1153(a) ), was approved prior to the date of the enactment of this Act, may be issued a visa pursuant to that paragraph subject to the availability of visas allocated to that category for fiscal year 2019. 2104. Allocation of immigrant visas for contingent nonimmigrants and children of certain nonimmigrants (a) In general Section 203 of the Immigration and Nationality Act ( 8 U.S.C. 1153 ), as amended by this title, is further amended— (1) by inserting after subsection (b) the following: (c) Adjustment for contingent nonimmigrants and children of certain nonimmigrants (1) In general Aliens subject to the worldwide level specified in section 201(e) for immigrants who shall be allotted visas in accordance with section 204(a)(1)(I)