The PDF Processing Fails to Use the DITA OT and Apache FOP

There are cases when publishing DITA content fails when creating a PDF file. This topic lists some common problems and solutions.

The FO processor cannot save the PDF at the specified target. The console output contains messages like:

[fop] [ERROR] Anttask - Error rendering fo file: C:\samples\dita\temp\pdf\oxygen_dita_temp\topic.fo <Failed to open C:\samples\dita\out\pdf\test.pdf>
Failed to open samples\dita\out\pdf\test.pdf
.............
[fop] Caused by: java.io.FileNotFoundException: C:\Users\radu_coravu\Desktop\bev\out\pdf\test.pdf 
(The process cannot access the file because it is being used by another process)

Such an error message usually means that the PDF file is already opened in a PDF reader application. The solution is to close the open PDF before running the transformation.

One of the DITA tables contains more cells in a table row than the defined number of colspec elements. The console output contains messages like:

[fop] [ERROR] Anttask - Error rendering fo file: D:\projects\eXml\samples\dita\flowers\temp\pdf\oxygen_dita_temp\topic.fo 
<net.sf.saxon.trans.XPathException: org.apache.fop.fo.ValidationException: 
The column-number or number of cells in the row overflows the number of fo:table-columns specified for the table. (See position 179:-1)>net.sf.saxon.trans.XPathException: org.apache.fop.fo.ValidationException: The column-number or number of cells in the row overflows the number of fo:table-columns specified for the table. (See position 179:-1)
[fop] 	at org.apache.fop.tools.anttasks.FOPTaskStarter.renderInputHandler(Fop.java:657)
[fop] 	at net.sf.saxon.event.ContentHandlerProxy.startContent(ContentHandlerProxy.java:375)
............
[fop] D:\projects\samples\dita\flowers\temp\pdf\oxygen_dita_temp\topic.fo -> D:\projects\samples\dita\flowers\out\pdf\flowers.pdf

To resolve this issue, correct the colspec attribute on the table that caused the issue. To locate the table that caused the issue:

Edit the transformation scenario and set the parameter clean.temp to no.
Run the transformation, open the topic.fo file in Oxygen XML Developer, and look in it at the line specified in the error message (See position 179:-1).
Look around that line in the XSL-FO file to find relevant text content which you can use, for example, with the Find/Replace in Files action in the DITA Maps Manager view to find the original DITA topic for which the table was generated.

There is a broken link in the generated XSL-FO file. The PDF is generated but contains a link that is not working. The console output contains messages like:
```
[fop] 1248 WARN [ main ] org.apache.fop.apps.FOUserAgent - Page 6: Unresolved ID reference "unique_4_Connect_42_wrongID" found.
```
To resolve this issue:
1. Use the Validate and Check for Completeness action available in the DITA Maps Manager view to find such problems.
2. If you publish to PDF using a DITAVAL filter, select the same DITAVAL file in the DITA Map Completeness Check dialog box.
3. If the Validate and Check for Completeness action does not discover any issues, edit the transformation scenario and set the clean.temp parameter to no.
4. Run the transformation, open the topic.fo file in Oxygen XML Developer, and search in it for the unique_4_Connect_42_wrongID id.
5. Look around that line in the XSL-FO file to find relevant text content which you can use, for example, with the Find/Replace in Files action in the DITA Maps Manager view to find the original DITA topic for which the table was generated.