A Long Term Extension Trial of BI 655066/ABBV-066 (Risankizumab), in Patients With Moderately to Severely Active Crohn's Disease

* Participants with Crohn's disease, who had successfully completed the preceding trial NCT02031276 (Boehringer Ingelheim trial 1311.6/AbbVie M15-993). Successful treatment is defined as: 1. Completion of period 2 in 1311.6 with a clinical response (drop in Crohn's Disease Activity Index (CDAI) from baseline by ≥100) but no remission (CDAI \< 150) at Visit E1; or 2. Completion of period 3 in 1311.6 with a clinical response (drop in CDAI from baseline by ≥100) and/or remission (CDAI \< 150) at Visit E5; or 3. Completion of period 2 or 3 in 1311.6 per protocol with a clinical response or remission before initiation of 1311.20 can roll-over either directly if that response/remission is maintained or through an open-label i.v. re-induction phase if they have lost their previous response/remission. * Female participants: 1. Women of childbearing potential (not surgically sterilized and between menarche and 1 year postmenopause), that, if sexually active agree to use one of the appropriate medically accepted methods of birth control in addition to the consistent and correct use of a condom from date of screening until 20 weeks after last administration of study medication. Medically accepted methods of contraception are: ethinyl estradiol containing contraceptives, diaphragm with spermicide substance, and intrauterine device, or 2. Surgically sterilized female participants with documentation of prior hysterectomy, tubal ligation or complete bilateral oophorectomy, or 3. Postmenopausal women with postmenopausal is defined as permanent cessation \>/=1 year of previously occurring menses, and 4. Negative serum ß-Human Chorionic Gonadotrophin test at screening and urine pregnancy test prior to randomization. * Male participants: 1. Who are documented to be sterile, or 2. Who consistently and correctly use effective method of contraception (i.e. condoms) during the study and 20 weeks after last administration of study medication. * Be able to adhere to the study visit schedule and other protocol requirements.

* Participants who were not compliant with key study procedures (colonoscopy, treatment compliance, endpoint assessment, contraception measures) in preceding trial 1311.6 * Participants who could not tolerate risankizumab (BI 655066/ ABBV-066) treatment for tolerability or safety reasons in the preceding trial * Are pregnant, nursing, or planning pregnancy while enrolled in the study, or within 20 weeks after receiving the last dose of study medication. * Participants must agree not to receive a live virus or bacterial or Bacille Calmette-Guérin vaccination during the study or up to 12 months after the last administration of study drug. * Participants who have developed malignancy, or suspicion of active malignant disease during the preceding trial * Are intending to participate in any other study using an investigational agent or procedure during participation in this study. * Cannot adhere to the concomitant medication requirements