If you are on OSGi, then please make sure you are using the correct flavor of Java 11, as per this link.Also, you can get the oracle jdbc jar from this link, and then you can convert it(or any other jar file) to OSGi bundle as per the instructions given in this link. Thanks!

You can't re-import the data into a signed form. Signed form is not supposed to be modified. Signing should be the last thing we do in a form.

You may use any one of these: initialize and form:ready .

I have done the same in the form below. Please check and confirm.https://drive.google.com/file/d/17-bYoAXdtMEp2lUFQ97EnR0DRgMKKhFg/view?usp=sharing 

Windows server 2010 was not supported even for ES4. So, ES2 didn't support 2010 too.Please refer to the following link for supported OS platforms, and choose the OS server accordingly, or upgrade/migrate LC server to AEM Forms.https://helpx.adobe.com/livecycle/help/livecycle-es4-supported-platforms....

You should use the OOTB reset button object to clear the form fields.Please refer to the following sample form for reference: https://drive.google.com/file/d/116z66FnFNZt-ExRyHvywyb5t9Oxdd61R/view?usp=sharing 

I have implemented the same in the sample form below. Please check and confirm if that is what you are expecting. Sample Form: https://drive.google.com/file/d/17-bYoAXdtMEp2lUFQ97EnR0DRgMKKhFg/view?usp=sharing 

I have reader extended a PDF with Adobe Acorbat Pro, in which I am hiding 2nd and 3rd page on form load, and making them visible on a button click, and it is working as expected in Acrobat Reader DC too. Please have a look at the form below. Sample form: https://drive.google.com/file/d/10Gn8HFjA1y31...

At which step in LCM are you getting this error? please share the complete error from the server logs.

Can you create a sample form(without any confidential data) similar to your original form, and share the same?