Float setting "Here definitely" in LyX with classicthesis class is not recognised when pdfLaTeX typesetting

[Former user]

Steps will reproduce the problem?
1.Insert a figure within a classicthesis class document in LyX V2.1.2 (These files
worked before upgrading from LyX V2.0.7)  
2. Have the figure float setting set to "Here Definitely" 
3. Document>View [PDF (pdfLaTeX)] or Ctrl+R

Expected output:- The pdf file in the viewer, as happens perfectly when "Here definitely"
is not selected

See instead:- Error message = LaTeX Error: Unknown float option `H'. Description  \begin{figure}[H]

Option `H' ignored and `p' used.

Versions:- {classicthesis}[2012/08/12 v4.1, LyX V2.1.2 with concurrently updated MiKTeX
7/11/2014, OS Win 7 enterprise


Additional information below.
It does not occur if the exact Latex source is cut from the LyX source panel and pasted
back into LyX as a TEX code insert! See .lyx file attached.
It does not occur for any class setting other than classicthesis.
I could not replicate in TexWorks  \documentclass{scrreprt} with the .tex file attached,
which worked fine.
If the LyX coded float is set to "Here Definitely" it detects the TEX coded floats
as the same error!!!! Other wise it doesn't give the error.
It is only the "Here Definitely" [H] placement option that is causing the error, with
all other otpions working fine.
I did notice in testing that the "Rotate Sideways" Float setting also produced the
error.
It crashed all my classicthesis files that worked fine with LyX V2.0.7 and the same
classicthesis version 4.1 that has not changed.
When updating LyX the latest MiKTeX packages are installed.
It seems to be LyX sending a different character (otherwise why just [H]) to the pdfLaTeX
typsetter than it does to its own source screen when classicthesis, and only classicthesis,
class is selected. How that is possible is beyond me, hence I post this issue. 
I noticed the [H] setting had been played with in a previous issue and wonder if it
may be treated differntly given it is the only "Must do" option.

TIA 

Original issue reported on code.google.com by alanjbelle on 2014-11-07 08:24:53 <hr> * Attachment: Float_figure_H.tex * Attachment: Float_figure_H.lyx

[Former user]

The newest fixltx2e package tackles the problem of missing options in \begin{figure}[htbp],
and reports an error if the option H (Here definitely) is encountered. This option
is only valid when the float package has been loaded. Seems that fixltx2e should be
used before any other packages as it fixes some core LaTeX bugs. LyX currently loads
float before classicthesis-config.tex (which itself loads fixltx2e). Removing \usepackage{fixltx2e}
from classicthesis-config.tex resolves the issue, but might introduce inconsistencies
elsewhere in the template.

Original issue reported on code.google.com by ivo.pletikosic on 2014-11-14 02:14:46

[André Miede]

fixltx2e is obsolete since mid 2015 as the fixes were introduced into the LaTeX kernel. fixltx2e was thus removed from classicthesis in version 4.2.

[Emiliano Heyns]

I've just downloaded the template and fixltx2e is still loaded in classicthesis-LyX-v4.2_biblatex_biber/classicthesis-config.tex

[André Miede]

fixltx2e was re-introduced because of some distribution "side-effects" and we forgot about this issue.

This will be addressed in the next release (hopefully).

[André Miede]

See also #107

[Ivo Pletikosić]

Now that fixltx2e does nothing, there are no issues with float package being loaded in LyX before classicthesis-config.tex, i.e. before fixltx2e.

[Ivo Pletikosić]

No action needed, fixltx2e has been discontinued.