# Legacy deserialization threw the following errors: **URL:** \ **Category:** Ignition\ **Created:** [March 18, 2010, 6:37pm UTC](https://forum.inductiveautomation.com/t/legacy-deserialization-threw-the-following-errors/1664 "2010-03-18T18:37:08Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Robert](https://avatars.discourse-cdn.com/v4/letter/r/e95f7d/32.png) [@Robert](https://forum.inductiveautomation.com/u/Robert)\ **Post date:** [March 18, 2010, 6:37pm UTC](https://forum.inductiveautomation.com/t/legacy-deserialization-threw-the-following-errors/1664/1 "2010-03-18T18:37:08Z")
After porting my project to Ignition, some screens are getting this error. ClassNotFoundException: com.inductiveautomation.factorypmi.application.FPMIWindow ---
**Author:** ![Carl.Gould](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/carl.gould/32/7262_2.png) [@Carl.Gould](https://forum.inductiveautomation.com/u/Carl.Gould)\ **Post date:** [March 18, 2010, 9:08pm UTC](https://forum.inductiveautomation.com/t/legacy-deserialization-threw-the-following-errors/1664/2 "2010-03-18T21:08:59Z")
Yes we just discovered this this morning. You can get around this by making sure that you do the following before you upgrade to Ignition: 1. Make sure you’re running the latest version of FactoryPMI 2. Go into the Designer in FactoryPMI, and use the “Re-serialize All” option under the Tools menu. 3. Save your project(s) 4. Now make your Gateway backup, and import it into Ignition. ---
**Author:** ![Robert](https://avatars.discourse-cdn.com/v4/letter/r/e95f7d/32.png) [@Robert](https://forum.inductiveautomation.com/u/Robert)\ **Post date:** [March 18, 2010, 10:27pm UTC](https://forum.inductiveautomation.com/t/legacy-deserialization-threw-the-following-errors/1664/3 "2010-03-18T22:27:24Z")
Thanks.