Some of the more common messages and codes passed by CLP are listed in the tables below. This is list is not meant to exhaustive. The notation is as for printf from "C":
Table 6.1. COIN Messages passed at or above logging level 1
Code  Area  Text and notes  

1  MPSREAD  At line %d %s  
This just prints out NAME line, ROW line, etc  
2  MPSREAD  Problem %s has %d rows, %d columns and %d elements  
This gives statistics after reading an MPS file  
8  MPSREAD  %s read with %d errors  
This gives error statistics for file  
505  PRESOLVE  Presolved poblem not optimal, resolve after postsolve  
This could be because it was not feasible or because of maximum iterations. If this message occurs then consider using primal clean up  
506  PRESOLVE  Presolve %d (%d) rows, %d (%d) columns and %d (%d) elements  
The first number is the number after presolve and the number in parentheses is amount of reduction  
510  PRESOLVE  Presolve is modifying %d integer bounds and represolving  
If presolve determines at the end that an integer variable have its bounds changed then it will repeat the entrire presolve  
511  PRESOLVE  After Postsolve, objective %g, infeasibilities  dual %g (%d), primal %g (%d)  
This gives the state after postsolve  this gives the objective value and the sum of dual and primal infeasibilities with the number of infeasibilities in parentheses. Hopefully these should be zero  
512  PRESOLVE  Presolved model was optimal, full model needs cleaning up  
If the numbers in previous message (511) were large then maybe we need to know, if small then that's life 
Table 6.2. CLP Messages passed at or above logging level 1
Code  Area  Text and notes  

1  SIMPLEX  Primal infeasible  objective value %g  
You may need to look at previous messages or use methods. Such as sumPrimalInfeasibilities() to find cause  
2  SIMPLEX  Dual infeasible  objective value %g  
You may need to look at previous messages or use methods. Such as sumDualInfeasibilities() to find cause  
3  SIMPLEX  Stopped  objective value %g  
The algorithm stopped as requested by the user.  
4  SIMPLEX  Stopped due to errors  objective value %g  
Switch on log level 2 to see information on size of elements etc. If they look reasonable then maybe we need to know.  
5  SIMPLEX  %d Obj %g Primal inf %g (%d) Dual inf %g (%d)  
At each refactorization this gives the number of iterations and the value of the objective function. If there are primal infeasibilities then the sum and number are given and similarly for dual infeasibilities. (This is a simplified form of message.)  
14  SIMPLEX  Perturbing problem by %g % of %g  
There is more to this message but if the user sees this then s/he has chosen to perturb the problem or the algorithm has decided to do so. If the numbers look too large the user may wish to think again.  
19  SIMPLEX  %d variables/rows fixed as scaled bounds too close  
If this occurs look carefully at your input data  
24  SIMPLEX  Matrix will be packed to eliminate small elements  
If this occurs the user should look carefully at data.  
26  SIMPLEX  Matrix will be packed to eliminate %d duplicate elements  
If this occurs the user should look carefully at data.  
28  SIMPLEX  Crash put %d variables in basis, %d dual infeasibilities  
 
29  SIMPLEX  End of values pass after %d iterations  
??? If primal(1) or dual(1) the a sweep through model is made and this signals end of pass. 
Table 6.3. COIN Messages passed at or above logging level 0
Code  Area  Text and notes  

3001  MPSREAD  Illegal value for %s of %g  
String will be "infinity" if setInfinity passed bad value, or "default integer bound" if setDefaultBound passed bad value.  
3002  MPSREAD  Bad image at line %d < %s >  
This gives line number and the offending line  
3003  MPSREAD  Duplicate objective at line %d < %s >  
An objective row appears twice in one column  
3004  MPSREAD  Duplicate row %s at line %d %s  
The named row appears twice in one column.  
3005  MPSREAD  No match for row %s at line %d < %s >  
The named row did not appear in ROWS section.  
3006  MPSREAD  No match for column at line %d < %s >  
The named column (in BOUNDS section) did not appear in COLUMNS section.  
6001  MPSREAD  Unable to open mps input file %s  
 
6002  MPSREAD  Unknown image %s at line %d of file %s  
The Mps reader could not make sense of the image file specified.  
6003  MPSREAD  Consider the possibility of a compressed file which zlib is unable to read.  
Some .gz files can not be read by zlib. Using gunzip and then gzip normally cures problem.  
6004  MPSREAD  EOF on file %s  
The Mps reader did not find expected section marker.  
6005  MPSREAD  Returning as too many errors  
The reader has put out 100 messages and is giving up.  
507  PRESOLVE  Presolve determined that the problem is infeasible with tolerance of %g  
If you want you can try with a larger tolerance  
508  PRESOLVE  Presolve thinks problem is unbounded  
Perhaps the user should maximize if initially minimizing or vice versa.  
509  PRESOLVE  Presolve thinks problem is infeasible AND unbounded???  
If you get this message we want to know 
Table 6.4. CLP Messages passed at or above logging level 0
Code  Area  Text and notes  

3002  SIMPLEX  Not solving empty problem  %d rows, %d columns and %d elements  
Test problem size before solving.  
6002  SIMPLEX  %d bad bound pairs or bad objectives were found  
Either the value in the objective was too large or a lower bound was greater than an upper bound.  
6003  SIMPLEX  Matrix has %d large values, first at column %d, row %d is %g  
Some of the values in matrix are ridiculous.  
6004  SIMPLEX  Can't get out of loop ...  

There are also messages available at log level 2 (the most likely useful relate to scaling), and will be addressed in a future version of this User Guide.