Hi all

We dist-upgraded Debian Stretch to Buster. PHP went from 7.0 to 7.4, Moodle from 3.5 to 3.9. STACK is 4.3.8 for Moodle 3.5+ 2020120600. I had to reinstall Maxima and Gnuplot which I got from the Debian repositories. Old STACK questions are still broken - with many errors similar to "The field ""Question text"" generated the following error: CASText failed validation. TIMEDOUT dumped)".

Here's the STACK healthcheck:

#### Check LaTeX is being converted correctly

Maths display method being used: MathJax.

STACK generates LaTeX on the fly, and enables teachers to write LaTeX in questions. It assumes that LaTeX will be converted by a moodle filter. Below are samples of displayed and inline expressions in LaTeX ...

#### Maxima configuration file

/* File generated on January 19, 2021, 8:03 pm */

/* Add the location to Maxima's search path */

file_search_maxima:append( [sconcat("/var/www/html/moodle/question/type/stack/stack/maxima/###.{mac,mc}")] , file_search_maxima)$

file_search_lisp:append( [sconcat("/var/www/html/moodle/question/type/stack/stack/maxima/###.{lisp}")] , file_search_lisp)$

file_search_maxima:append( [sconcat("/var/www/data/moodledata/stack/logs/###.{mac,mc}")] , file_search_maxima)$

file_search_lisp:append( [sconcat("/var/www/data/moodledata/stack/logs/###.{lisp}")] , file_search_lisp)$

STACK_SETUP(ex):=block(

MAXIMA_VERSION_NUM_EXPECTED:43.2,

MAXIMA_PLATFORM:"linux",

maxima_tempdir:"/var/www/data/moodledata/stack/tmp/",

IMAGE_DIR:"/var/www/data/moodledata/stack/plots/",

PLOT_SIZE:[450,300],

PLOT_TERMINAL:"svg",

PLOT_TERM_OPT:"dynamic font \",11\" linewidth 1.2",

DEL_CMD:"rm",

GNUPLOT_CMD:"/usr/bin/gnuplot",

MAXIMA_VERSION_EXPECTED:"5.43.2",

URL_BASE:"!ploturl!",

/* Define units available in STACK. */

stack_unit_si_prefix_code:[y, z, a, f, p, n, u, m, c, d, da, h, k, M, G, T, P, E, Z, Y],

stack_unit_si_prefix_multiplier:[10^-24, 10^-21, 10^-18, 10^-15, 10^-12, 10^-9, 10^-6, 10^-3, 10^-2, 10^-1, 10, 10^2, 10^3, 10^6, 10^9, 10^12, 10^15, 10^18, 10^21, 10^24],

stack_unit_si_prefix_tex:["\\mathrm{y}", "\\mathrm{z}", "\\mathrm{a}", "\\mathrm{f}", "\\mathrm{p}", "\\mathrm{n}", "\\mu ", "\\mathrm{m}", "\\mathrm{c}", "\\mathrm{d}", "\\mathrm{da}", "\\mathrm{h}", "\\mathrm{k}", "\\mathrm{M}", "\\mathrm{G}", "\\mathrm{T}", "\\mathrm{P}", "\\mathrm{E}", "\\mathrm{Z}", "\\mathrm{Y}"],

stack_unit_si_unit_code:[m, l, L, g, t, s, h, Hz, Bq, cd, N, Pa, cal, Cal, Btu, eV, J, W, A, ohm, C, V, F, S, Wb, T, H, Gy, rem, Sv, lx, lm, mol, M, kat, rad, sr, K, VA, eV, Ci],

stack_unit_si_unit_conversions:[m, m^3/1000, m^3/1000, kg/1000, 1000*kg, s, s*3600, 1/s, 1/s, cd, (kg*m)/s^2, kg/(m*s^2), 4.2*J, 4200*J, 1055*J, 1.602177e-19*J, (kg*m^2)/s^2, (kg*m^2)/s^3, A, (kg*m^2)/(s^3*A^2), s*A, (kg*m^2)/(s^3*A), (s^4*A^2)/(kg*m^2), (s^3*A^2)/(kg*m^2), (kg*m^2)/(s^2*A), kg/(s^2*A), (kg*m^2)/(s^2*A^2), m^2/s^2, 0.01*Sv, m^2/s^2, cd/m^2, cd, mol, mol/(m^3/1000), mol/s, rad, sr, K, (kg*m^2)/(s^3), 1.602176634E-19*J, Ci],

stack_unit_si_unit_tex:["\\mathrm{m}", "\\mathrm{l}", "\\mathrm{L}", "\\mathrm{g}", "\\mathrm{t}", "\\mathrm{s}", "\\mathrm{h}", "\\mathrm{Hz}", "\\mathrm{Bq}", "\\mathrm{cd}", "\\mathrm{N}", "\\mathrm{Pa}", "\\mathrm{cal}", "\\mathrm{cal}", "\\mathrm{Btu}", "\\mathrm{eV}", "\\mathrm{J}", "\\mathrm{W}", "\\mathrm{A}", "\\Omega", "\\mathrm{C}", "\\mathrm{V}", "\\mathrm{F}", "\\mathrm{S}", "\\mathrm{Wb}", "\\mathrm{T}", "\\mathrm{H}", "\\mathrm{Gy}", "\\mathrm{rem}", "\\mathrm{Sv}", "\\mathrm{lx}", "\\mathrm{lm}", "\\mathrm{mol}", "\\mathrm{M}", "\\mathrm{kat}", "\\mathrm{rad}", "\\mathrm{sr}", "\\mathrm{K}", "\\mathrm{VA}", "\\mathrm{eV}", "\\mathrm{Ci}"],

stack_unit_other_unit_code:[min, amu, u, mmHg, bar, ha, cc, gal, mbar, atm, torr, rev, deg, rpm, au, Da, Np, B, dB, day, year, hp, in, ft, yd, mi, lb],

stack_unit_other_unit_conversions:[s*60, amu, amu, 133.322387415*Pa, 10^5*Pa, 10^4*m^2, m^3*10^(-6), 3.785*l, 10^2*Pa, 101325*Pa, 101325/760*Pa, 2*pi*rad, pi*rad/180, pi*rad/(30*s), 149597870700*m, 1.660539040E-27*kg, Np, B, dB, 86400*s, 3.156e7*s, 746*W, in, 12*in, 36*in, 5280*12*in, 4.4482*N],

stack_unit_other_unit_tex:["\\mathrm{min}", "\\mathrm{amu}", "\\mathrm{u}", "\\mathrm{mmHg}", "\\mathrm{bar}", "\\mathrm{ha}", "\\mathrm{cc}", "\\mathrm{gal}", "\\mathrm{mbar}", "\\mathrm{atm}", "\\mathrm{torr}", "\\mathrm{rev}", "\\mathrm{{}^{o}}", "\\mathrm{rpm}", "\\mathrm{au}", "\\mathrm{Da}", "\\mathrm{Np}", "\\mathrm{B}", "\\mathrm{dB}", "\\mathrm{day}", "\\mathrm{year}", "\\mathrm{hp}", "\\mathrm{in}", "\\mathrm{ft}", "\\mathrm{yd}", "\\mathrm{mi}", "\\mathrm{lb}"],

true)$

/* Load the main libraries. */

load("stackmaxima.mac")$

print(sconcat("[ STACK-Maxima started, library version ", stackmaximaversion, " ]"))$

#### Uncached CAS call

##### Debug info

##### Context used

Platform: linux Maxima shell command: maxima --use-version=5.43.2 Maxima initial command: load("/var/www/data/moodledata/stack/maximalocal.mac"); Maxima timeout: 10

##### Maxima command

cab:block([],print("[STACKSTART Locals= [ 0=[ error= ["), cte("CASresult",errcatch(diff(x^

n,x))), print("1=[ error= ["), cte("STACKversion",errcatch(stackmaximaversion)), print("2=[ error= ["), cte("MAXIMAversion",errcatch(MAXIMA_VERSION_STR)), print("3=[ error= ["), cte("MAXIMAversionnum",errcatch(MAXIMA_VERSION_NUM)), print("4=[ error= ["), cte("externalformat",errcatch(adjust_external_format())), print("5=[ error= ["), cte("CAStime",errcatch(CAStime:"2021-01-19 20:03:51")), print("] ]"), return(true));

#### CAS process return value: 139

##### Timings

Start: 1611083031.5708, End: 1611083032.2135, Taken = 0.64268612861633

##### CAS result

Segmentation fault (core dumped)

unpack_raw_result: no STACKSTART returned. Data returned was: Segmentation fault (core dumped) ]]]]

##### Unpacked result as

Array ( )