# biber error: "bcf is malformed, last biblatex run probably failed. Deleted

I'm writing a paper on overleaf. I got an error message:

(no line number):
[0] Config.pm:343> INFO - This is Biber 2.5
[0] Config.pm:346> INFO - Logfile is 'filename.blg'
[42] biber:290> INFO - === Wed Apr 11, 2018, 13:41:14
[164] Utils.pm:165> ERROR - filename.bcf is malformed, last biblatex run probably failed. Deleted filename.bbl
[164] Biber.pm:113> INFO - ERRORS: 1


Everything worked very well (including references and bibliography) and I suddenly got this error at what seemed like an arbitrary point (just writing standard text, no references or anything). When I delete the text everything works again.

\usepackage[british]{babel}
\usepackage{csquotes}
\usepackage[backend=biber,style=apa]{biblatex}
\DeclareLanguageMapping{british}{british-apa}


and I have \printbibliography at the end of my document, but removing it doesn't solve the problem.

The last words in the log file are:

<fig_name.jpg, id=33, 824.07875pt x 631.35875pt>
File: fig_name.jpg Graphic file (type jpg)

<use fig_name.jpg>
Package pdftex.def Info: fig_name.jpg used on input line 299
.
(pdftex.def)             Requested size: 426.79134pt x 326.97899pt.

LaTeX Warning: Citation 'meuwese2014subjective' on page 5 undefined on input li
ne 300.

LaTeX Warning: Citation 'meuwese2014subjective' on page 5 undefined on input li
ne 300.

[5 <./SDT.png>]

./filename.tex:302: LaTeX Error: Float(s) lost.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
...

l.302 \end{figure}

Here is how much of TeX's memory you used:
24590 strings out of 493013
492167 string characters out of 6135682
964956 words of memory out of 5000000
27686 multiletter control sequences out of 15000+600000
11931 words of font info for 41 fonts, out of 8000000 for 9000
1141 hyphenation exceptions out of 8191
62i,9n,92p,1438b,1663s stack positions out of 5000i,500n,10000p,200000b,80000s

./filename.tex:302:  ==> Fatal error occurred, no output PDF fi
le produced!


The reference it complains about does actually exist in the bibtex file:

@article{meuwese2014subjective,
title={The subjective experience of object recognition: comparing metacognition for object detection and object categorization},
author={Meuwese, Julia DI and van Loon, Anouk M and Lamme, Victor AF and Fahrenfort, Johannes J},
journal={Attention, Perception, \& Psychophysics},
volume={76},
number={4},
pages={1057--1068},
year={2014},
publisher={Springer}
}


and was used before in the document without an error coming up.

• You have an error regarding float objects such as figure or table: LaTeX Error: Float(s) lost.. If that error interrupts the TeX run you won't get a .bcf file. You need to get to the bottom of the floats lost error and resolve it. – moewe Apr 11 '18 at 14:01
• – moewe Apr 11 '18 at 14:07
• Any news here? At the moment we can't really say more than that you need to find your lost floats and fix the whatever caused them. – moewe Apr 13 '18 at 9:43

The real problem here is the first error message you get

./filename.tex:302: LaTeX Error: Float(s) lost.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
...

l.302 \end{figure}


This aborts the TeX run on your document. In particular this causes the .bcf file, through which biblatex and Biber communicate, to get corrupted. The .bcf file is only completed at the very end of your document. If you don't get there because an error stops TeX earlier, the .bcf will be incomplete and Biber will fail to make sense of it. Biber notices this and responds to this situation by deleting the .bbl file

ERROR - filename.bcf is malformed, last biblatex run probably failed. Deleted filename.bbl


The .bbl file contains the data of all citations in a format readable for biblatex. If that file is deleted that means that all citations will end up undefined.

So you will have to make sure that your .tex file can be compiled without error. You will have to find the lost floats: http://www.tex.ac.uk/FAQ-fllost.html, How to find the lost text part when having "Float(s) lost" error, Floats lost error.

In general, when Biber complains about a malformed .bcf file, chances are your LaTeX run aborted with some fatal error. The .bcf file is used to pass information from LaTeX to Biber and it is written anew in every LaTeX run. The first bits of the file are written right at the beginning of the document processing and it is only finalised and closed at the very end of the document. This means that the file is very susceptible to errors during a LaTeX run, as basically any error between the beginning and the end of the document can stop the file from being written out correctly.

Whenever Biber encounters this problem it will delete the .bbl file for you. This is a sort of service since the problematic code that caused the LaTeX run to fail may hide in the Biber-produced .bbl file. In any case if you encounter this error, simply rerunning Biber is not going to fix anything. You need to find out why the .bcf is malformed. Usually this is due to a LaTeX error that should be reported in the .log of the LaTeX run and that should be fixed. Fix the error, delete all temporary files (.aux, .bbl, .bcf, ...) and rerun the full LaTeX, Biber, LaTeX, LaTeX cycle.